TL;DR: Fine enough game, I remember having a lot of fun with experimenting different strategies for upgrading and customizing my guy to survive the harder levels. A genuinely (and usually fairly) difficult game when I was much younger, I believe it'd still pose a challenge for someone more seasoned with 2D shooters.

A bit buggy, though that might as well be par for the course for these kinds of games. Never bad enough to deter me from trying to play it on crappy library and school computers, though. Give it a try if you're ever on Y8.