I forgot the name, was on a 8086 machine. You controlled a little diamond shaped character and have to squish enemies shaped like the letter H (on higher levels with double outlines) between moveable and immovable blocks. Later they also lay eggs that would hatch faster and faster.
Fennec is even better than Firefox, it's the same source but recompiled to allow all add-ons in the main app. So basically a stable Firefox nightly, if you wish.
It's maintained by the folks behind the f-droid app store themselves, so arguably a highly trusted source.
Sync to Firefox desktop fully implemented and working.