I added to my Tetris clone a FLEX branch, it only uses the compiler and not the FLEX class containers (unnecessary for this little game). The point is you can use the free API tools to make a simple game like this, without needing the Flash IDE at all.
It's cool these days to bash anything Adobe related (and the bloated PDF reader or the security holes in the Flash player of course doesn't help). Just for the record this page can crash your browser (Click on it only if you feel lucky and don't have something to lose). That is a bug that has not been fixed since 2008, and there are many others out there (but with a less spectacular failure outcome). The sad truth is that anybody working (and I mean earning his bread) with Flash technology can tell you scary stories about classes refusing to compile, library assets getting mysteriously corrupted, different movie behavior under different player versions, etc. And if you are angry today I can assure you the bugs were a lot uglier in the AS2 times.
However, in all honesty, I don't dislike Flash technology, of course hitting a Flash bug makes you feel angry until you find the workaround, but you would learn from your experiences and you would start avoiding the things that don't work, after some time you would have earned an impressive list of best-practices and things to avoid, following that path, working with Flash can be actually a nice experience. I personally like their API design, at the very least they have invested a lot of time and thinking in that.