I think for mouse controls it'd be click and drag the blue ball into position and then release to fire it off. If you've got a less crashy version then I'd definitely be up for playing it!
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I'll play around with that when I've got some time.
I've got it fixed, but can't post it here till after the jam per the rules. In game, the crashing seems to happen when the timer gets to 2 minutes in a level, so you should be able to pause and retry the level before this happens. You can see the timer in "Time Attack" mode, it's not visible in "Par" but it's still running.