Grimrock

If the construction kit allows players to custom design a party before entering a dungeon, then it would be possible for people to "port" their own designed dungeon from pen-and-paper modules they might have designed for games like D&D for example, and insert higher level characters with set spells, equipment and stats.

What I would see happening would be much smaller (2-5 levels) dungeons being made to be more of a quick session games then a prolonged dungeon crawl, with much tighter puzzles (as the party has much more controlled capability) more interesting items (as they are tailored for that particular dungeon), and far less less need for inventory management.

This way, many old PnP modules could also be modded and ported over as well I guess.

Have you ever played a game called Deadly Rooms of Death? It's all puzzle and has an active player community that makes a lot of custom maps. There's definitely a lot that can be done with very simple basic building blocks. Once you pair things down it's much simpler to make pure puzzles.

I suspect the first fan made dungeons we get will be single level. It'll take a while I guess to make larger ones.

Daniel.