"I'm not interested in that kind of work" is a fair answer, but it seems pretty rude to dismiss it as an ugly hacky legacy code base without reviewing it first.
For the record, I looked at the Wesnoth codebase in college, so my opinions are outdated (by 5+ years) but not unfounded.
Rather, I'm merely repeating why I didn't help then, instead of particularly why now, which is a much more boring "I'm just busy".
I suppose it's possible the codebase has changed so much in those years that the answers are no longer relevant, but they would be the only open source project (not sponsored by a corporation) I'm aware of that happening in.
