Back
How Spiral House Created the “TMNT Dimensions [ROGUELIKE]” Series in Fortnite
The Fortnite Team
TMNT Dimensions [ROGUELIKE] and TMNT Dimensions 2 [ROGUELIKE] are Fortnite islands created using Unreal Editor for Fortnite (UEFN) that draw inspiration from classic Teenage Mutant Ninja Turtles (TMNT) games (with a twist!) inspired by the roguelike genre. These action-packed experiences pay homage to the arcade beat ‘em ups of the past while introducing fresh mechanics.
In this blog post, Bobby Earl from Spiral House takes you behind the scenes to explore how the team leveraged UEFN features and tools alongside the TMNT templates and assets to develop these Turtle-y awesome islands for Paramount Games Studios.
Bobby Earl, Technical Director at Spiral House: We chose to create a beat 'em up because we wanted to recreate the iconic old-school gameplay of classic TMNT games — and we knew UEFN was the perfect tool to make that happen. We took inspiration from the TMNT arcade games we grew up playing and added a modern twist drawn from some of our favorite roguelike experiences.
We’re genuinely excited to be working with UEFN again — it gives us the ability to accurately capture the flavor and style of other games while blending them into the Fortnite universe.
We created a custom distance-based animation system, where each attack animation includes a predefined distance and apex time. While an animation plays, [the system] continuously [checks] the player’s distance, making sure damage is applied at the correct point of the animation and within the correct range.
We created a base state-driven NPC behavior script and then derived from this to create a variety of enemy types, each with unique animations, patterns, and play styles. This enables us to share basic combat/elimination logic while still providing flexibility for different behaviors.
At the end of the animation, we spawn a new crate, which is then animated [to be thrown]. [We run] a collision check to damage any players it hits.
We also implemented a knockback system using moving platforms that tracks players and enemies in real time. When a character is hit, they are dragged in the appropriate direction, giving players breathing room in intense fights.
We developed our own damage/health layer to give us control over individual weapon damage and health. This approach makes it possible to have individual stat upgrades and use values that fit the balancing of our game. We use the Conditional Button device to determine which weapon the player is using and then base core combat mechanics on that. This [prods] players to use the correct weapon to defeat certain “Elite” enemy types.
To keep combat engaging, we created a Behavior Choreographer device, which dynamically grants [“attack tokens” to and revokes them from] enemies based on their position in the scene, their proximity to the player, and their current state. Each player has a limited number of tokens, which helps prevent enemies from simply swarming the player. The idea is to instead give them a chance to employ skill and tactics to beat the level.
For Elite enemy NPCs, we used control rigs to ensure that the VFX followed them smoothly. We attached the Elite enemy shield VFX to a control rig, [using] a single-bone skeleton that follows an invisible “control prop” that we can move around the scene. We then teleport the control prop (which controls the control rig and the attached VFX) to the Elite enemy.
Because the control rig runs client side, the motion appears much smoother than if we simply moved the VFX.
A new addition to TMNT Dimensions 2 [ROGUELIKE] is the trap system. Different arenas feature various background interactions that function as environmental traps. These include directly dangerous elements (like exploding barrels) and visual traps (such as collapsing rigging). These dynamic elements provide new ways to defeat enemies and keep gameplay fresh by transforming the environment in unexpected ways.
We designed our arenas around five worlds: the Sewers, New York City, the Technodrome, Dimension X, and Fortnite (drawing inspiration from both Fortnite OG and regular Fortnite Battle Royale).
To display all the required stats, we had to push the limits of UEFN/Verse UI. We used images to represent text and effects that otherwise wouldn’t be possible, and combined UI devices with Verse UI to create a dynamic, engaging interface.
We also created a custom slider class that supports multiple modes of operation (vertical, horizontal, image-based, etc.), enabling us to build UI elements like the dynamic enemy health bar, the threat meter, and the ally meter.
The number of enemies in each wave is determined by “spawn points,” a value that increases as arenas are completed. Enemies are divided into ranks, with higher-ranked enemies requiring more spawn points per unit. This system prevents the number of enemies spawned from becoming overwhelming.
As the game progresses, higher-ranked enemies become available. In the early arenas, only lower-ranked enemies — like base Foot Clan enemies and fiends — appear. In later arenas, higher-ranked enemies, such as Sai Foot Clan enemies, are introduced. Together, ranks and spawn points ensure that difficulty starts low and scales infinitely, providing a consistent challenge as players push for higher arena completion counts.
To add a more handcrafted feel to the waves that spawn, we developed a wave template system. Wave templates store information about the enemy archetypes to spawn, the ratios between archetypes, and the relative ranks between the archetypes to spawn.
Using this, we’re able to produce waves made up of enemies that work well together whilst still enabling the difficulty to scale endlessly — for example, a wave might consist of one shield enemy for every two ranged enemies.
To break up the endless mode, various bonus rounds appear every three arenas, alternating between minigame and boss rounds.
Minigames offer a fun way to earn more coins and work as a team. We’ve developed 10 unique minigame ideas that players can vote on, such as Car Smash or Gold Goblin.
The recurring boss rounds present more opportunities for challenging combat and [heightened] player satisfaction. Rather than fighting through 20 arenas to reach Shredder, players only need to progress through six arenas before encountering their first boss. What’s more, the boss’ difficulty scales with the current arena number, keeping the fights challenging yet fair.
After each arena, players can choose one of three boosters. Boosters are small stat boosts that last until the run is over, giving players a sense of choice and progression in every run.
Boosters come in two forms: normal boosters (the ones you gain after each arena) and timed boosters. Timed boosters offer a more powerful boost to your stats but only last for five minutes. They can be obtained in four ways: using coins at April’s booster shop that appears . . .when an arena is complete, completing a minigame, when a run ends, or through daily rewards.
When all players are defeated and the run ends, players are offered a choice between two timed boosters. These provide temporary boosts to the players stats, encouraging them to start another run. . . .
That’s all from us at Spiral House — we hope you enjoy playing TMNT Dimensions 2 [ROGUELIKE]!
(Island code: 0564-2509-4966)
Want to start creating your own TMNT islands — or supercharge your existing one? We’ve just added four new TMNT characters (Krang, Casey Jones, Bebop and Rocksteady), expanded storytelling and gameplay functionality, and added a Starter Island template that includes a Technodrome Prefab, landscape materials, VFX and much more. Grab your nunchaku, dive in, and find out more at our recent TMNT blog post!
In this blog post, Bobby Earl from Spiral House takes you behind the scenes to explore how the team leveraged UEFN features and tools alongside the TMNT templates and assets to develop these Turtle-y awesome islands for Paramount Games Studios.
Bobby Earl, Technical Director at Spiral House: We chose to create a beat 'em up because we wanted to recreate the iconic old-school gameplay of classic TMNT games — and we knew UEFN was the perfect tool to make that happen. We took inspiration from the TMNT arcade games we grew up playing and added a modern twist drawn from some of our favorite roguelike experiences.
We’re genuinely excited to be working with UEFN again — it gives us the ability to accurately capture the flavor and style of other games while blending them into the Fortnite universe.
Combat
To bring the essence of classic beat ’em up gameplay into UEFN, we leveraged the NPC Spawner device, enabling us to script behavior for different NPCs.We created a custom distance-based animation system, where each attack animation includes a predefined distance and apex time. While an animation plays, [the system] continuously [checks] the player’s distance, making sure damage is applied at the correct point of the animation and within the correct range.
We created a base state-driven NPC behavior script and then derived from this to create a variety of enemy types, each with unique animations, patterns, and play styles. This enables us to share basic combat/elimination logic while still providing flexibility for different behaviors.
Advanced Animation
To enhance immersion, we leveraged the NPC animation controller to create unique hit, knockdown, and attack animations for each enemy type. For instance, the unarmed Foot Clan enemy appears to pick up a crate, but this is achieved using a clever trick: a small, scaled-down crate is embedded within the mesh, which enlarges during the pickup animation.At the end of the animation, we spawn a new crate, which is then animated [to be thrown]. [We run] a collision check to damage any players it hits.
We also implemented a knockback system using moving platforms that tracks players and enemies in real time. When a character is hit, they are dragged in the appropriate direction, giving players breathing room in intense fights.
Balancing and Tuning the Game
Balancing was a crucial part of the game, and as development progressed, we needed a more efficient way to manage stats on a larger scale. This led us to create a Balance data device, which reads data from a CSV file and allows us to access stats from various parts of the game, such as enemy waves, enemy damage, weapon damage, etc.We developed our own damage/health layer to give us control over individual weapon damage and health. This approach makes it possible to have individual stat upgrades and use values that fit the balancing of our game. We use the Conditional Button device to determine which weapon the player is using and then base core combat mechanics on that. This [prods] players to use the correct weapon to defeat certain “Elite” enemy types.
To keep combat engaging, we created a Behavior Choreographer device, which dynamically grants [“attack tokens” to and revokes them from] enemies based on their position in the scene, their proximity to the player, and their current state. Each player has a limited number of tokens, which helps prevent enemies from simply swarming the player. The idea is to instead give them a chance to employ skill and tactics to beat the level.
For Elite enemy NPCs, we used control rigs to ensure that the VFX followed them smoothly. We attached the Elite enemy shield VFX to a control rig, [using] a single-bone skeleton that follows an invisible “control prop” that we can move around the scene. We then teleport the control prop (which controls the control rig and the attached VFX) to the Elite enemy.
Because the control rig runs client side, the motion appears much smoother than if we simply moved the VFX.
A new addition to TMNT Dimensions 2 [ROGUELIKE] is the trap system. Different arenas feature various background interactions that function as environmental traps. These include directly dangerous elements (like exploding barrels) and visual traps (such as collapsing rigging). These dynamic elements provide new ways to defeat enemies and keep gameplay fresh by transforming the environment in unexpected ways.
Arenas
To overcome the challenge of implementing 24 arenas within the memory constraints, . . ., we used two tools: Data Layers and World Partition. Each arena exists on a separate Data Layer which is dynamically loaded and unloaded as the game progresses, helping to save memory. We also use World Partition to spatially load and unload actors as the player moves around the scene, keeping memory usage as low as possible.We designed our arenas around five worlds: the Sewers, New York City, the Technodrome, Dimension X, and Fortnite (drawing inspiration from both Fortnite OG and regular Fortnite Battle Royale).
Roguelike
A core component of the game is the persistent upgrade system, enabling players to keep their . . . upgrades for permanent stat increases. This system works using Verse Persistence, enabling us to track various stats, including those not directly adjusted by the upgrades such as total eliminations, ally summons, and more. These stats are used to drive the quest and achievement system, providing a more engaging experience.To display all the required stats, we had to push the limits of UEFN/Verse UI. We used images to represent text and effects that otherwise wouldn’t be possible, and combined UI devices with Verse UI to create a dynamic, engaging interface.
We also created a custom slider class that supports multiple modes of operation (vertical, horizontal, image-based, etc.), enabling us to build UI elements like the dynamic enemy health bar, the threat meter, and the ally meter.
Game Flow
We’ve made a number of changes to the game flow since [the first] TMNT Dimensions, with the most significant being that the game is now endless. Instead of fighting to reach the final arena and winning the game, the goal is to progress as far as possible, battling through randomized arenas with dynamically generated waves of enemies based on your current progression.The number of enemies in each wave is determined by “spawn points,” a value that increases as arenas are completed. Enemies are divided into ranks, with higher-ranked enemies requiring more spawn points per unit. This system prevents the number of enemies spawned from becoming overwhelming.
As the game progresses, higher-ranked enemies become available. In the early arenas, only lower-ranked enemies — like base Foot Clan enemies and fiends — appear. In later arenas, higher-ranked enemies, such as Sai Foot Clan enemies, are introduced. Together, ranks and spawn points ensure that difficulty starts low and scales infinitely, providing a consistent challenge as players push for higher arena completion counts.
To add a more handcrafted feel to the waves that spawn, we developed a wave template system. Wave templates store information about the enemy archetypes to spawn, the ratios between archetypes, and the relative ranks between the archetypes to spawn.
Using this, we’re able to produce waves made up of enemies that work well together whilst still enabling the difficulty to scale endlessly — for example, a wave might consist of one shield enemy for every two ranged enemies.
To break up the endless mode, various bonus rounds appear every three arenas, alternating between minigame and boss rounds.
Minigames offer a fun way to earn more coins and work as a team. We’ve developed 10 unique minigame ideas that players can vote on, such as Car Smash or Gold Goblin.
The recurring boss rounds present more opportunities for challenging combat and [heightened] player satisfaction. Rather than fighting through 20 arenas to reach Shredder, players only need to progress through six arenas before encountering their first boss. What’s more, the boss’ difficulty scales with the current arena number, keeping the fights challenging yet fair.
After each arena, players can choose one of three boosters. Boosters are small stat boosts that last until the run is over, giving players a sense of choice and progression in every run.
Boosters come in two forms: normal boosters (the ones you gain after each arena) and timed boosters. Timed boosters offer a more powerful boost to your stats but only last for five minutes. They can be obtained in four ways: using coins at April’s booster shop that appears . . .when an arena is complete, completing a minigame, when a run ends, or through daily rewards.
When all players are defeated and the run ends, players are offered a choice between two timed boosters. These provide temporary boosts to the players stats, encouraging them to start another run. . . .
That’s all from us at Spiral House — we hope you enjoy playing TMNT Dimensions 2 [ROGUELIKE]!
(Island code: 0564-2509-4966)
Want to start creating your own TMNT islands — or supercharge your existing one? We’ve just added four new TMNT characters (Krang, Casey Jones, Bebop and Rocksteady), expanded storytelling and gameplay functionality, and added a Starter Island template that includes a Technodrome Prefab, landscape materials, VFX and much more. Grab your nunchaku, dive in, and find out more at our recent TMNT blog post!