Chess Against the Engine

Chess against a proper engine, with two features that most browser chess leaves out. The first is the evaluation bar down the side, which tells you who is actually winning while you play rather than after you lose — the fastest way there is to learn what a bad move looks like. The second is take back, which turns a game into an exercise: play the move, watch the bar drop, take it back and find the one that does not. Pick white or black, legal moves highlight themselves, and the engine is strong enough to be worth the lesson.