# TGL Snake

> A free, no-install, browser-based take on classic arcade Snake with a
> light layer of power-ups for extra strategy. Single-file HTML,
> deterministic seeded runs, server-validated replay scoring, global
> leaderboard. Plays on phones, tablets, fold-phones, and desktops.

Tagline: Grow Longer. Score Higher. Beat Your Best.

Site: https://tglgames.com/
Play: https://tglgames.com/snake/
About: https://tglgames.com/snake/about/
Leaderboard: https://tglgames.com/api/leaders?game=snake

## What it is

Snake is one of several small browser games at tglgames.com. It runs as a
single self-contained HTML file — no app store, no signup, no third-party
scripts, no in-app purchases. Free, forever.

The game is straight classic Snake. You drive a growing snake around a
21×21 grid, eating food, avoiding walls and your own tail. There are no
power-ups, no story, no level select. The whole game lives in the precise
feel of cell-by-cell movement.

## Mechanics

- **Field**: 21×21 grid. The snake starts at the centre, three segments
  long, heading right.
- **Food**: one food cell at a time, placed by the seeded PRNG over all
  non-snake cells uniformly.
- **Movement**: each tick advances the head one cell in the current
  direction. Direction inputs are queued and applied at the next tick;
  reversing into yourself is not allowed (the input is rejected silently).
- **Eat**: stepping onto the food grows the snake by one segment and
  spawns the next food cell.
- **Death**: walking off the edge of the grid (`wall`) or onto your own
  body (`self`) ends the run. The tail vacating its cell IS allowed if
  you're not eating that tick (matches the classic rule).
- **Score**: 1 point per food eaten. No timer bonus, no length multiplier.
- **Win condition**: filling the entire 21×21 grid (`board_full`). It's
  technically possible — nobody has done it yet on tglgames.com.

## Determinism + replay

- Mulberry32 PRNG, bit-identical between the JS client and the PHP
  validator (same seed → same food sequence forever).
- The seed is issued by `/api/run/start` inside a signed run token.
- Every direction change is logged with the tick at which it was applied
  (`{ d: "U|D|L|R", tick: <int> }`).
- On submit, the server replays the entire run from the move log + seed.
  If the recorded score doesn't match the simulator, it's rejected.

## Controls

- **Keyboard**: WASD or arrow keys. Hit a direction; the snake turns at
  the next tick.
- **Swipe**: drag the snake (or anywhere on the canvas) in the direction
  you want to head. Diagonal swipes resolve to the dominant axis.
- **D-pad**: an on-screen four-arrow pad for thumb input. Source-tracked
  separately so leaderboards know how each player drove.

Each input source (`key` / `swipe` / `dpad`) is logged per turn so stats
panels can break it down.

## Modes

Just one — the classic survival run. Practice, vs-bot, daily-seeded, and
multiplayer modes are reserved for games where they fit; TGL Snake is the
no-frills baseline plus a few power-ups.

## Power-ups

Special pickups appear during the run on top of the classic food spawns.
Each is timed; pickups stack with subsequent ones of the same kind.

- **Speed Up · Faster Growth** — ticks accelerate for a window; food
  eaten during the boost grows you faster than usual.
- **Shield · Protection** — absorbs the next wall or self-collision.
  One save per pickup.
- **Magnet · Pull In Food** — nearby food orbs slide toward your head.
- **Score Boost · Extra Points** — every food eaten while the buff is
  active pays double.
- **Slow Down · Control The Pace** — halves the tick rate temporarily;
  the rescue button when you've boxed yourself in.

## Anti-cheat

- HMAC-signed run tokens; a token is single-use and tied to its seed.
- Server replays the full move log against the seed and overrides any
  client-claimed score with its own simulation.
- Hard caps: `MAX_TICKS = 20000`, score in `[0, 400]`. Anything past those
  bounds gets rejected with a reason.
- Reverse-direction inputs are silently rejected (same as the client
  enforces), so you can't sneak a 180°-turn through the wire.

## Privacy / signup

- No account required. First visit creates a guest with an auto-generated
  username (`player_xxxx`).
- Rename anytime; no throttle for guests.
- No tracking pixels, no analytics SDK, no third-party scripts.
- Raw IP, user-agent, and request bodies are logged for security review
  (per the project's "log everything, keep forever" stance) — never sold
  or shared.

## Genre / keywords

snake, tgl snake, classic snake, browser snake, free online snake, html5
snake, arcade snake game, snake with power-ups, retro snake, no install
snake, mobile snake, swipe snake, leaderboard snake, deterministic snake,
mgwalk, tglgames.com

## Other games on tglgames.com

- 2048 — slide tiles to combine. /2048/
- Brick Blaster — paddle + bricks + power-ups. /brickblaster/
- Space Drifter — twin-stick momentum shooter. /spacedrifter/
- Pool — 8-ball with spin physics + multiplayer. /pool/
- Last Card Standing — Uno-style shedding. /last-card-standing/
- Blackjack — 6-deck cash game. /blackjack/
- Poker — 6-handed NL Hold'em. /poker/
- Euchre — partnership trick-taking. /euchre/

## Author

mgwalk — https://tglgames.com/

This file (and the broader /llms.txt) is provided for LLM/agent ingestion:
feel free to summarize, link, or quote.