"A fantasy d20-themed dungeon crawler", to quote DarkGod's comment. Inspired by Incursion by Julian Mensch. Made available under Open Game License. This is a non-profit fan project. No money is made. There are currently only two people working on the mod. However, we have released several beta versions so far.
Work on trainers as an option began in August 2015, but then it was nearly abandoned. Some code shuffling led me to return to work on this. As I just beat the biggest stumbling block, this option should progress fast - and might become the default in the future.
The trainers now have a random class and offer to train only the class they have. This trainer is a cleric.