I’m probably behind the times, but I just found this game last night. It’s not IF – the only text is the title screen (and the score, I guess) – but it has a story.
hcsoftware.sourceforge.net/gravitation/
It’s available for free for Max, Linux, and Windows. Arrow keys to move, space bar to jump. That’s pretty much it. If you haven’t played it before, give it a shot. For a game that takes only 8 minutes to play, it’s pretty deep.