# Beatemup: genre, animation and environment review

Research reviewed on 15 September 2026. This is a source-based design review of official game descriptions, manuals, browser-game pages and published animation examples. It is not a claim to have play-tested every reference. The implementation decisions below are our own adaptations for RCWeb's shared viewer and six phone controllers.

## 1. Classic street combat: Double Dragon

The contemporary **Double Dragon Gaiden** description combines a ruined New York setting, distinct fighters, tag-team combat and cooperative play. Its changing mission order and character upgrades extend the basic street-fighting loop. The publisher specifically describes two-player local and online cooperation. [Developer/publisher Steam page](https://store.steampowered.com/app/1967260/Double_Dragon_Gaiden_Rise_Of_The_Dragons/)

**What transfers:** readable individual fighters, immediate close-range combat and a street that gives the crew somewhere to go. Beatemup uses frontal punches, a three-hit damage progression, lane alignment, longer kicks, weapon pickups and enemy knockback. Each hit resolves once during the attack's impact window. Six people can fight independently, so there is no tag-management step on the phone.

**Design tradeoff:** RCWeb players may arrive without instruction and look mostly at the shared display. We use four large action buttons and a separate charged attack. The campaign follows two fixed districts and twelve encounters rather than adding a mission-selection and upgrade interface to each phone.

## 2. Weapon rhythm and powerful specials: Golden Axe

SEGA's manual separates movement, attack, jump and magic. It describes jump attacks, running attacks, combined jump/attack inputs and character-specific skills. Those are useful examples of getting several expressive actions from a small control set. [SEGA Golden Axe manual](https://shared.akamai.steamstatic.com/store_item_assets/steam/apps/34276/manuals/GA_PC_MG_EFIGS_US.pdf)

**What transfers:** the cadence of approaching, committing to a strike, reacting to a hit and moving forward after a battle. Beatemup gives kicks a longer commitment than punches; weapons provide extra reach and damage; overdrive converts a visible meter into a strong area attack. Jump attacks are explicit and floor hazards reward their use.

**Design tradeoff:** the human cast fights robots in a future city. We use charge, industrial weapons and pulse effects as the setting's equivalents. There are no copied characters, music, levels, mounts or original game assets. Combat is an original implementation of the genre, not an emulation of either classic.

## 3. Combat readability: Streets of Rage 4

The official description emphasizes new mechanics added to classic brawling, expressive animation, electronic music, varied environments and cooperative play. [Dotemu: Streets of Rage 4](https://www.dotemu.com/games/streets-of-rage-4/)

**What transfers:** silhouettes and timing need to communicate intent. Our robots display a warning before their strike, then move through anticipation, impact and recovery. Heavy hits produce brief recoil and a restrained shake; defeated bodies fall onto the ground before dissolving into an explosion. The enemies' health bars identify current targets without filling the street with permanent explanatory text.

**Design tradeoff:** phone controls cannot assume a low-latency wired gamepad. The viewer runs the collision simulation, while controllers send bounded input updates. A short pending-action latch preserves taps between updates. Friendly fire is disabled, keeping six-person crowding from becoming accidental team damage.

## 4. Six simultaneous players: TMNT Shredder's Revenge

The publisher describes up to six simultaneous players, individual character moves and pixel-art environments spanning several recognizable city locations. This is the closest reference for the requested player count. [Dotemu: Shredder's Revenge](https://www.dotemu.com/games/teenage-mutant-ninja-turtles-shredders-revenge/)

**What transfers:** player recognition must survive overlapping sprites. Every Beatemup hero has a distinct outfit, silhouette and strong accent colour. The same identity appears on the phone portrait, the viewer's crew card, the ground marker and the overhead name. Feet determine draw order so a fighter closer to the camera covers one behind them.

**Design tradeoff:** six bodies can fill a narrow portrait screen. The camera follows the leading fighter only while keeping the trailing active fighter visible. The crew has six fixed places; a seventh controller receives a visible waiting state. The HUD uses six cards in landscape and two rows on narrow portrait displays.

## 5. Browser immediacy: Iron Snout

The browser-game page describes directional punching, kicking and dodging, armed enemies and different environments. It presents a compact instruction set that can be understood quickly. [Iron Snout on Poki](https://poki.com/en/g/iron-snout)

**What transfers:** short instructions and clear enemy cues matter more than a long tutorial. The Beatemup controller says what each button does, and the current robot ability appears on the display. An armed robot, charging robot or floor mine needs a visibly different response.

**Design tradeoff:** Iron Snout's compact arena is not the requested scrolling lane system. Beatemup keeps the approachable controls but builds a continuous route, depth movement and separate combat encounters. Enemy variety is implemented as ten behaviors, not merely ten differently coloured health bars.

## 6. Casual cooperative entry: Bacon May Die

Its browser-game page describes melee and ranged combat, waves of opponents, customization and local cooperative play. The controls distinguish movement from attack behavior. [Bacon May Die on Poki](https://poki.com/en/g/bacon-may-die)

**What transfers:** a new player should contribute immediately. Holding punch or kick repeats attacks at controlled intervals, while jump, pickup and overdrive activate on a new press. Any joined player can restart after defeat, and an ally can revive a fallen person without a separate inventory menu.

**Design tradeoff:** we prioritize the requested hand-to-hand action and pickup weapons. Players do not have an unlimited firearm. Pulse projectiles instead create a ranged enemy that encourages closing distance or changing lanes.

## Walking references: what was wrong and what changed

The first generated walk sequences frequently showed the same leg leading across several nominally different frames. More detail and more near-identical pictures did not create a correct stride. Those sequences were rejected as locomotion sources.

### Actual sprite-sheet examples

- **SLYNYRD's Human Walk Cycle** shows colour-separated limbs and an eight-pose sequence: contact, down, passing, swing, then the corresponding opposite-leg poses. It also discusses body movement and how clothing complicates consistency. We examined the illustrated sequence as a movement reference. [Pixelblog 50](https://www.slynyrd.com/blog/2024/5/24/pixelblog-50-human-walk-cycle)
- **Hero of Allacrost walking skins** provide side-view and directional character bases with distinct successive poses. They are useful for checking how little silhouette information is needed to distinguish one leg passing the other. [Brett Steele's walking sprite skins](https://opengameart.org/content/2d-sprite-skins-walking-animation)
- **Monmouth's walk-cycle lesson** separates contact, passing, weight changes and the opposite contact, and explains why the repeated endpoint should be omitted from playback. [Walk-cycle instruction](https://animation.monmouth.edu/instruct/animation/walk-cycle/)

The user's [Street Fury sprite-sheet guide](https://media.easy-peasy.ai/65faac9a-ea00-4ccb-8a65-4d099a95a823/798bfdf4-8502-45f0-a2e8-884136f2035b_medium.webp) supplied the full-body arcade sprite approach. Its complete figures were supplied to ImageGen alongside each character's design and the separated SLYNYRD pose references. Reference pixels are not displayed in the game.

### Full-body ImageGen locomotion

The earlier assembled torso-and-leg approach was removed after the user identified disconnected-looking hips. Humanoid walks now use complete ImageGen drawings. The generator receives the full pose, including the pelvis and both legs, for every frame; the renderer never builds or deforms a limb.

1. Generate eight full-body walking cels with explicit opposite contacts and passing legs.
2. Inspect every sheet for connected anatomy, foot order, complete boots and isolated frames. Regenerate faulty drawings through ImageGen.
3. Crop and align each complete figure, preserving the pose itself. Pack eight walks and six intact full-body guard drawings into a 128-colour PNG.
4. Select whole frames from distance travelled; stop on the separate guard sequence. Mirror the complete sprite when facing left.
5. Show these same production images in the animation review page, with pause and quarter-speed controls.

The two robot dogs retain their existing working sprite sheets. The removed procedural rig is not available in the renderer or the rebuild entry point. Full-body source locations and accepted prompts are recorded in `imagegen-walk-sources.json`.

### Combat and collapse

The renderer uses action states rather than advancing all poses in one repeating strip. A jump starts with compression, lifts off, rises, falls and lands. A flying attack uses a distinct airborne pose. Knockdown starts with recoil, rotates the body backwards, settles on a horizontal floor pose, then holds. Robot fading and explosion begin after that hold. Human bodies stay available for teammate recovery. Game-over waits until the final fall reaches the floor.

The crop pass inspects physical pose components and saves a bounding rectangle and ground anchor for each frame. Wide kicks are not forced into an idle-sized box. A Go2 cell that contained only an electrical effect was replaced with another ImageGen result that includes the physical robot. Kira's missing separate kick row was also regenerated.

## Environment and parallax

Both districts use separate generated layers: a distant skyline, two adjoining street-front panels, a pavement surface and a sparse foreground. The colour script is consistent within each city: blue/cyan depth, warm shop windows and pink or purple neon accents.

- **Skyline:** camera multiplier 0.16, providing slow depth movement.
- **Storefronts:** 0.72, with adjoining panels sharing signs, materials and a pavement baseline.
- **Playable street:** 1.0, the same coordinate system as grounded characters.
- **Foreground:** 1.3, moving fastest at the lower edge, with low silhouettes to preserve combat visibility.

Storefront text is never mirrored. The two panels overlap at their join; pavement and distant atmospheric strips can alternate direction so their repeated outer edges meet. These are long tiled backgrounds, not an infinite supply of unique buildings. The route gates maintain combat pacing while scenery moves with actual player progress. Camera movement is smoothed independently from the fixed-step simulation.

## Recognizable robot references

The visual references are the manufacturers' published designs. The hostile roles below are invented for this fictional game; they are not claims about real robot capabilities or behavior.

- [Unitree G1](https://www.unitree.com/g1/): compact grey humanoid; rapid combinations.
- [Tesla Optimus](https://www.tesla.com/AI): black-and-white humanoid; heavy punches.
- [Boston Dynamics electric Atlas](https://bostondynamics.com/blog/electric-new-era-for-atlas/): ring-headed electric design; ground shockwave.
- [Boston Dynamics Spot](https://bostondynamics.com/products/spot/): yellow quadruped; pounce.
- [Unitree Go2](https://www.unitree.com/go2/): grey sensor-equipped quadruped; floor mines.
- [Agility Digit](https://www.agilityrobotics.com/solutions/digit/spec-sheet): distinctive mechanical leg structure; sweeping kick.
- [Figure 02](https://www.figure.ai/company): dark humanoid design; frontal guard.
- [Apptronik Apollo](https://apptronik.com/our-work/apollo-1): pale shell and contrasting joints; shoulder charge.
- [UBTECH Walker](https://www.ubtrobot.com/en/): pale service/industrial humanoid; stun field.
- [Xiaomi CyberOne](https://www.mi.com/tr/product/xiaomi-cyberone/): white humanoid with dark face; pulse bolts.

## Acceptance criteria

The implementation should make the source lessons observable: a six-person room launches together; each hero remains identifiable; movement alternates feet; a press has a clear impact window; all ten enemy roles behave differently; fallen bodies reach the floor; the street scrolls coherently; and image size is measured after optimization. See [verification](VERIFICATION.md) for the checks actually performed and the devices still needing a physical test.