Chromium B.S.U.

About the game

Chromium B.S.U. is a vertical shooter with one unusual rule: nothing may get past you. You command the cargo ship Chromium B.S.U. on its way to the front line, and you fight from a distance through a small fleet of robotic fighters. Every enemy that reaches the bottom of the screen attacks the cargo ship and costs you one of those fighters.

That rule changes how you play. Instead of dodging and waiting for a clear shot, you hunt every ship down, and sometimes the best move is to fly straight into one. Your fighter is a weapon too: crashing into an enemy destroys it, and when a fighter is lost the cargo ship launches the next one with a burst of energy that clears everything nearby.

Waves of fighters, gunships and armoured tanks pour down over metal decks and open sea, and each level ends with a large boss. Your fighter always fires a pair of basic guns, and the skull power-ups add ammunition for three more weapons: extra machine guns, an ion cannon that cuts through rows of enemies and a plasma repeater, the strongest gun in the game, which empties its ammunition quickly.

Mark B. Allan released the game in 2000. It was later picked up by volunteers, who replaced the sounds and music with free ones, cleaned up the code and kept it running on new systems; the sounds and music are the work of Brian Redfern.

Playing it here

This is version 0.9.16.1, the latest release, compiled for the browser from the project's source code. The download is about 3 MB. The game draws its 3D scenes with its own graphics code, rewritten here for the browser, and uses the free Chakra Petch font for its text. Settings and high scores are kept in this browser; clearing this site's data deletes them. The game is in English.

Click the game to start steering with the mouse: the browser locks the pointer to the game while you play, and Escape frees it. The player's own full-screen button is the way to play full screen; the full-screen option in the game's menu is not available here.

Controls

In the menu, the arrow keys choose an option and change its value, and Enter on "new game" starts playing. You can also click the options.

Getting started

Pick a skill level. The menu offers eight of them, from "fish in a barrel" to "impossible". "Normal" is the default; the easier ones give you more time to learn how the waves move.

Start from level one. The level option only lets you pick levels you have already reached, so a new player starts at the beginning. Each level is a little faster and denser than the last.

Watch the sides of the screen. The bars on the left and right track your ammunition, shields and damage, and the fighters waiting on the cargo ship are shown at the top right.

Tips

Never let anything through. A ship that slips past costs a whole fighter, far more than the damage you take by ramming it. When an enemy is about to escape, fly into it.

Self-destruct to save your ammunition. A fighter that blows itself up first throws out its stock of ammunition, which the next fighter can collect. The new fighter also arrives with an energy burst that clears the area, so a well-timed self-destruct can rescue a bad situation.

Not every power-up is worth catching. The shield icons, told apart by the color of their glow, restore your shields, repair damage or give you super shields, a short spell of extra protection. Each of them can also be left alone: a shield that drifts past the bottom of the screen is worth 10,000 points, and letting the super shields go by earns an extra fighter instead.

Save the plasma for the boss. The plasma repeater hits hardest but burns through its ammunition fast. The basic guns never run out, so lean on them for the smaller enemies.