Unfortunately, I came across FlashChess3 a while ago. It’s a fairly decent online chess engine, and I enjoy it alot. I mostly play the ‘casual’ level because I beat it most of the time without too much effort (not the best way to get better, I know). Some nice features are the possibility to play both colours (I used to play another online engine where I was always white; I got better white white, but am still terrible with black) and the possibility to undo moves such that I can keep playing games even though I do stupid mistakes I’d never do ‘for real’ (I hope). It also annotates the games, which is nice; I guess the feature is more developed in the download-version. What I don’t like is the irrationally aggresive pawns several online engines seem to feature on low levels of difficulty.