[sackerhews]

I opened it in a new tab. By the time I looked at the tab it was in full epilepsy induction mode. Thankfully I don't suffer from it.

Perhaps don't start the game until it receives a focus.

[mkrecny]

Yes I understand this is a bit problematic.

[prezjordan]

Not a bit! Could be life-threatening. I'm unsure what the flashing does, but please reconsider it?

EDIT: Just checked and the effect is only visible on Firefox. Works fine in Chrome.