My favorite part of "Bill & Ted's Excellent Adventure" came when they figured out the paradoxes of time travel and, simply by saying "Must remember to bring a trash can!" one appears in Ted's hands and he stuffs it over a bad guy's head.

Not that you can do any of that in "Chronotron," but the idea is the same, think in the present, giving orders to yourself in the past. Sort of. In Chronotron, the idea is to Clone multiple versions of yourself, using a time machine, to get through a puzzle level. The catch - all past versions will spawn and recreate your actions, so you need to think in chronological order for each step of the puzzle, and leave enough time for your final self to get through the gates and ride the risers to your objective.

It's a hell of a fun flash game - my co-worker showed it to me yesterday, so I can vouch for its productivity killing effect.

Chronotron [Addicting Games]