[1] More information and Gameboy Advance and Windows conversions are available at Jamie Woodhouse's website: http://www.qwak.co.uk (the Gameboy Advance version is sold out now)
[2] The game has 80 unique levels and repeats them with changed numbers (level 1 becomes level 81 etc) after level 80/160/240 etc has been finished.
During a one player game when you die and have no more credits, press fire on the joystick in the mouse port to restart the game on the level you last died on.