3 worlds collide - more science fiction. Physiological scifi - how would differing evolutionary histories & life cycles affect morality?
Alexander Wales
Dark Wizard of Donekirk - really good one
Worth The Candle - Alexander Wales - 180+ chapters of isekai roleplaying game. A regular guy finds himself living inside a world inspired by his many years of dungeon mastering. Extremely developed magic system with ~50 different types. It's a great exploration of many different types of mechanics.
Shadow of the Limelight - finished story by Alexander Wales.
Glimwarden - unfinished story by Alexander Wales, which starts off great.
The Last Christmas - fun and pretty short, but he really should have used the power of the infinite time machine portal better.
The Metropolitain Man - really good rational version of superman.
Others
Delve by SenescentSoul - isekai with lots of min/maxing D&D style. Really fun, pretty light although gets more serious later. Speculation whether this is by an alt of Wales. Ongoing, 70+ chapters.
Cordyceps by Benedict_SC - really good writing. Pretty different than the others.