Released on; C64 in 1983.
Text taken from this page of the Llamasoft blog:
So my first ever C64 game was rather obscure and not terribly amazing, but it was all done in one evening the first night I got the machine set up.
On the old Vic 20 I’d written a little game called ROX that me and my dad enjoyed playing quite a lot one Christmas.
Although I’m not sure if we ever even sold it on the Vic ourselves since we really didn’t like that much selling programs written in ropey old BASIC.
However since at that time there was basically nothing at all out on the C64 I thought it might be an idea to release Rox on the 64 as a BASIC program that other users could LIST to see how the new chips worked themselves. We did end up selling it for a while on the 64, just at a low price so that people wouldn’t think we were trying to take the piss.
So my first C64 program was a pretty low-key and unassuming thing, but it was a first step on what was to be a long and enjoyable road.