Thanks everyone for your answers! On a second look, the forum looked a bit stale, so I was worried I posted in a dead place for a minute.
The reason I asked is actually less because I'm looking for a way to play RMXP games (got a windows partition for that, tried with wine but that just crashes always),
but more because I recently started a clean-room (no RE!) implementation, which I'd like to work on as a hobby.
I'm really just talking about the RGSS engine here (sorry, title might have been misleading >.>) that plays the final game.
So if there was like already some major project going, I'd rather have invested my time in improving that.
There's this
Google Code page that I found, but it's dead-empty, and somehow I'm even unable to pinpoint how old it is.
Other than that, there is of course the ARC project (which is linked somewhere in this forum as well I believe), but they seem to have a different goal.