I had a list of some flash games I used to obsess over, but I can’t find it right now. I’ll throw Sonny 2 as my recommendation, I beat that game many times and I still come back to it every now and then. It’s a top-tier RPG.
I would also recommend Gemcraft and Bloons TD, but they have premium sequels now that are way better than the web games.
TheImpressiveX