Tunnel Rat: Causing Trouble in Two Worlds

Volumes 1 to 4 of Tunnel Rat are Available on KU. Volume 5 will be coming out the end of 2026. 
(Which means the chapters in Volume 5 come off of RR sometime in the 4th quarter.)

https://www.royalroad.com/amazon/B0D98TW5F2?maas=&ref=



Milo lives in a steel cave within a man-made mountain of steel and concrete. He spends his days repairing the machinery that keeps the habitat livable and tinkering with the prosthetics that help his twisted body move about through the small tunnels and air shafts that are his world. He's as much a piece of discarded machinery as the equipment he keeps running. He likes to fix things, which is good because he sometimes breaks things.

But lately, he's been getting bored, and for a super-genius, that's a bad thing. Luckily, the criminals he escaped from are back. Stealing everything from them will keep him busy, especially when he steals a new MK7 immersion pod used to enter the world of Genesis. Milo has always lived in the tunnels, and now he's a Tunnel Rat in looks, not just name. He wants to go deep into the world and find the ancient mysteries left by races that delved deep and stayed below.

He'll find new mysteries to solve, new friends, things to fix, terrifying creatures to aggravate, and things to break. Hopefully, he fixes more than he breaks, or this new world might be in trouble.

And thanks to the artist of that handsome rat for inspiration. Find more of her work here: https://www.deviantart.com/watch/memymine/deviations