A game engine for game jams

Why Griff

Most engines make you stop the game to change it, lose your changes when play mode ends, and break undo in creative ways. Griff is built around a few promises.

The game keeps running while you change it

Save a C# script and every instance of it is swapped in the running game within a moment. Public properties carry over and the game doesn’t restart; a compile error leaves the last good version running and points at the line.

Levels painted in the Scene view

Tilemaps square, isometric or hex, in layers, with autotiles and slopes, painted with a brush, rectangles and fills. Prefabs, sprites drawn in the Sprite Painter and sounds made in the Sound Maker, all without leaving the editor.

Rewind, breakpoints and stepping

Griff keeps the last 20 seconds of play: drag back to just before the bug, tweak something and resume. Breakpoints cost nothing, a script that throws stops at the line that threw, and you step a line at a time into the next frame.

Undo covers everything, and play can't hurt your work

Every change goes through one undo history, even across a script reload. Play runs on a copy of the scene; Stop puts everything back, and Keep Play Changes copies the values you found while playing into your scene.

Build with an agent

While it’s open, the editor serves the Model Context Protocol, so an agent like Claude Code can build games with it. Every command, component, window and panel is a tool, and anything added later shows up by itself.

The same game on every machine

The game moves in fixed steps whatever the screen’s frame rate, and is drawn smoothly between them: smooth on a 144 Hz screen, and the same input gives the same result anywhere.

Multiplayer for every kind of game

Host or join over the local network or the internet, or run a dedicated server. Each player moves their own character at once, and Griff’s components work for every player, from platformers to strategy.

One click to ship

Build Game makes a single .exe that carries everything, .NET included, so players install nothing. Build Small Game makes a 4 MB one for players who have the .NET Desktop Runtime.

Play the templates

Every template is a whole game, playable and audible from the first second, and every one is playable right here: click a card to open it and play in your browser. In Griff’s editor you pick one in New Project and change it into yours, and Build for Web exports your own game the same way.

PlatformerRun, jump and dash across platforms, swing a sword and come back at the last checkpoint.Play in your browserTop-downExplore a torch-lit dungeon in eight directions, with a bat on your tail.Play in your browserIsometricA sunny courtyard seen at a slant, with walls to walk behind and a crate to push.Play in your browserArcadeBlast waves of enemies in an arena, with a menu, options and a high score.Play in your browserStrategyReal-time strategy: workers gather and build, barracks train armies, and a computer opponent comes out of the fog.Play in your browserShooterA first-person shooter whose levels are painted top-down.Play in your browserSandboxA block world made from a seed to dig up and build in, with caves, ores and crafting.Play in your browserContraptionBuild machines in a room full of props: wheels, thrusters, ropes, hinges and logic gates.Play in your browserPuzzlePush crates onto the marks in four Sokoban levels.Play in your browserPhysicsPull back the slingshot and topple towers of wood, glass and stone onto the grubs inside.Play in your browserPinballMidnight Midway: a pinball table at a night carnival, with bumpers, a skyway and a bell to ring.Play in your browserMatch-3Swap gems into lines that clear, fall and refill in chains, over four levels.Play in your browserFalling BlocksPieces of four slide, turn and drop; full rows clear and it all speeds up.Play in your browserRoguelikeDungeons made from a seed, floor after floor, where everything moves when you do.Play in your browserTacticsPick a unit, see how far it can walk and hit, and send it to fight.Play in your browserRPG StatsA turn-based battle worked out from tables: classes, spells, items and enemies.Play in your browserFighterDojo Clash: a one-on-one fighting game for two at one keyboard or against the computer.Play in your browserRhythmNeon Pulse: press each lane as its notes cross the line, to three songs at three difficulties.Play in your browserCardsA card duel against the computer: creatures, spells and mana that grows every turn.Play in your browserAdventureWhere's Pip? A short point-and-click adventure: three rooms, a neighbour to talk to, and a cat up a tree.Play in your browserVisual NovelStarfall Café: a short visual novel about a star that fell into the flour.Play in your browserMultiplayerAn arena shooter for up to eight players, on one network or over the internet.Play in your browserBunnyMarkA benchmark: how many bunnies can this computer bounce at 60 frames a second?Play in your browser

Games start when you click them, so this page stays light, and sound starts with your first click or key. Network play isn’t available on the web; each game’s page says what it takes and how it plays. All games

Open source

Griff is open source under the MIT License. Its code and issues are on GitHub, and every release is on the Releases page.

RepositoryIssuesReleasesLicenseDocs