It's not about learning. More like fixing the bugs. The only thing you would probably learn from ADOM's source code is how not to write code that produces lot of bugs.
The fact is that I haven't yet released my main roguelike project. I'm not worried about success though. It's going to be a gardening simulator mainly, with some roguelike influences. If I like it I'm happy.you can't bear the fact that ADOM is more successful than your game is.