Smoosh Bros

A Super Smash Bros–style two-player fighting game built entirely in SystemVerilog on an FPGA

640×480 VGA • Hardware Sprites • Real-Time Physics • Fully Parallel Game Engine

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Overview

Smoosh Bros is a fully hardware-accelerated fighting game implemented in pure SystemVerilog.
There is no CPU, no firmware, and no software loop of any kind.

Every frame of gameplay is produced directly in FPGA logic:

• Movement & physics
• Collision & platform logic
• Hit detection
• Shields
• Health & stock tracking
• Sprite animation
• VGA rendering

The entire game engine runs fully in parallel, synchronized to the VGA clock.

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Gameplay Features

Player Systems

• Responsive two-player controls
• Smooth horizontal movement with acceleration
• Full jumping + falling animations
• Attack system with active hit frames
• Real-time health bars
• Stock-based life system
• Shield ability with decay, cooldown, and break
• Accurate platform collision
• Clean animation transitions:
  idle → walk → run → jump → fall → attack

Rendering

• 640×480 @ 60 Hz VGA output
• Hardware HSYNC/VSYNC generation
• Background + platforms stored in ROM
• Character sprites stored in block ROM
• Alpha-style transparency masking
• Pixel-accurate renderer composed in hardware

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Controls

Action	Button
Move Left	Left
Move Right	Right
Jump	B
Attack	A
Shield	Custom mapped input

NES-style digital controllers supported through hardware interface.

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FPGA Pin Assignments

VGA sync signals

set_io hsync 25 set_io vsync 23

external clk

set_io clk_in 20

set_io latch1 28 set_io latch2 43 set_io ctrl_clk1 38 set_io ctrl_clk2 45 set_io data1 42 set_io data2 36

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Build Instructions

1. Install the toolchain

apio install system apio install scons apio install icestorm apio install nextpnr-ice40 apio install oss-cad-suite

2. Build the project

apio build

3. Upload to the FPGA

apio upload

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How the Hardware Game Engine Works

Every frame, the game logic executes as a fully pipelined hardware system:

1. Controller inputs are sampled
2. Movement FSM updates velocity, gravity, & position
3. Attack FSM activates hitboxes and frame timing
4. Shield FSM performs decay, break, and cooldown logic
5. Collision engine resolves platforms & hit detection
6. Health/stock logic updates player state
7. Animation state machine chooses correct sprite frame
8. Renderer selects pixels from background/platform/sprite/mask
9. VGA controller outputs the final RGB pixel

Everything runs continuously and in parallel — the FPGA is the game engine.

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Future Improvements

Planned extensions include:

• Directional hitboxes & variable damage
• Special moves and projectiles
• Additional platforms and stage layouts
• Improved UI and hit effects
• Hardware sound output
• Win/results screen

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Made by Vaughan, Andrew, Jonah, and Daniel