Drilling Billy was the brainchild of Piet Kargaard, the programming was done by Troels Nordfalk, music and sound effects by David Filskov (who now maintains a sort of official website for the game). Piet Kargaard then created the Hugo series of games for ITE Media, based on a popular TV show, again with music and sound effects by David Filskov. For Troels Nordfalk, I found no evidence that he was ever involved in another game project.
OS/2?
Yes, Drilling Billy was available in an OS/2 version as well. In 1996, Piet Kargaard told the OS/2 e-Zine:
To be honest with you, the OS/2 version came about as a coincidence. When I looked for a programmer for Drilling Billy I had only the DOS version in mind, but as it turned out that programmer was an OS/2 fan and he argued strongly for an OS/2 version. As a coincidence I'm an old Amiga fan myself and I can see the wisdom in releasing software to a devoted but neglected market like OS/2.
There was even an OS/2 demo, which can still be downloaded from Norloff's OS/2 BBS, but you need a subscription. For the full game, there was a seperate OS/2 executable which you could use after doing a DOS install. It didn't work all too well, mainly because OS/2 wasn't a good platform for games that were intended to run fullscreen. Read the OS/2 e-Zine review for details.
