Grav Wars

Two ships. One universe. Every shot bends.

Take turns firing missiles across a universe of planets, stars and black holes. Gravity curves every shot: slingshot round a planet, skim a black hole's photon sphere, or watch your missile spiral into the horizon. The first pilot to hit the other ship wins the round.

Features

• Real orbital physics: Newtonian gravity plus Einstein's correction near black holes, so orbits precess into rosettes.
• Ray-traced black holes: light bends around them on screen, with a glowing accretion disk and Einstein rings of whatever is behind.
• Five kinds of stars: pulsars whose beams shove your missile, binary stars that move mid-shot, red giants you can fly through, white dwarfs and main-sequence suns.
• Two views: classic 2D, or press V to tilt space up into a 3D spacetime sheet.
• Play a friend or the CPU: two pilots on one device, or a CPU opponent at three skill levels.
• Music made from the math: a Fibonacci melody, planets that hum their orbits, and a missile whose voice drops as its clock slows near a horizon.
• Plays anywhere: computers and phones held sideways. No download, no account.

How to play

• Aim: drag from anywhere. The direction sets the angle, the distance sets the speed. Or type exact numbers, like the 1989 original.
• Fire: the FIRE button, Space or Enter.
• Correct: your last shot stays on screen. See how it bent, adjust, and fire again.
• Press H in the game for every control and a tour of the physics.

The physics

Planets pull with Newton's inverse-square law, and their colour is their density, as in the original game. Near a black hole the game adds the Schwarzschild correction, a = −GM/r² · (1 + 3L²/c²r²), so orbits precess, light can circle the hole at 1.5 Schwarzschild radii, and nothing orbits stably inside 3. Light is slow in this universe (missiles reach 0.67c), so time dilation shows up in every match.

The full explanation, with universes to try: gravwars.com/how-it-works

Remaking a 1989 classic

Inspired by Gravity Wars (1989) by Sohrab Ismail-Beigi, a DOS game released to the public domain. This version keeps its rules (angle and speed, planet colour is density, shots that fly off screen and come back) and adds everything else.

Play full screen, or install it

Use the full-screen button at the bottom right of the game, or play at gravwars.com. On a phone, Add to Home Screen there installs it as an app that also plays offline.

Found a bug or have an idea? Leave a comment below. For a bug, the game's ! button can copy a report with the details (your device, the universe and your shots) to paste in. This is an early build and every report helps.