[official website]
[credits & legal info]
[hints]
[more hints - spoiler warning]
[official time attack rules - spoiler warning]
You must play the game from start to end without pausing or continuing from a saved game. The final time is the time it takes from pressing the OK button in the menu, to the moment the "the end" anvil crashes at you. No cheats allowed.
The rules for a time attack+ are identical, although you must also make it trough SoulEye's Secret once or more. No cheats allowed.
The rules for a time attack ultra+ are just like time attack+, except that you also need to trigger Funky Mode Lite, Super Funky Mode, and have seen the De_Gopher picture. By the way, you are ALLOWED to use the cheat you learn in SoulEye's Secret.