I love mr driller and have never seen a clone.
A clone exists, his name is Miss Driller.
http://adas.lolipop.jp/digit/index.php?MissDriller
I think it is an open source project as it as been ported on linux, windows and Dreamcast. It uses SDL. Unfortunaly most of website are in Japaneese.
Concerning the Shareware , and who pays. Usually, i pay for all solftware i use regulary even if i have already an illegal fullversion. I try the sofware with the copy, and if it is really good i buy it. Even for certain game i bought it after having complete the game on the "pirate" full version. (I did that with Duke Nukem 3d). I wanted to thanks developpers for the fun they gave me!
I develop for years, retro games, utilities, front End... i never really win money with donation. But since Atomic, i didn't receive lot of money, but lot of old computers, video game cartiridghe, Arcade PCB, and other contribution for my collections.