I've been running a duet play by post game based on Tunnel Goons for nearly a year.
We've explored Levi Kornelson's Goon Deeps, kicked around the surface city of Sargolis, traveled overland and visited with the ghosts of one of the characters' parents, delved my own Catacombs under the thriving city of Nalastis, went overland again, and now are exploring the city of Antali (home to one of the characters).
The rules are simple, yes, but they support quite sophisticated play in a logical manner. Maybe they are good for complex situations because they are simple, so there's not really edge cases or loopholes or exploits so much as opportunities to make common sense rulings.
Honestly, I've been in several Tunnel Goons games now and I find them refreshing and easy.