He called it 'Panzer General Forever' (or 'PG Forever', and often referred to as 'PGF'). He did this all without changing the underlying structure he tried as hard as possible to replicate the game faithfully. Along the way he also tweaked the UI to make the game nicer to play, and added a better AI player. Then it would work on modern versions of Windows, at higher resolutions, etc. In 2009 (actually he started earlier than that) a guy known as Rudankort decided that rather than try to hack the game to get it to his liking, he'd simply rewrite it. SSI went on to release several more versions of the game (all part of the '5-star' series) with the same basic concepts and gameplay in different settings.

It was also a lot easier to get into than many other wargames. It was never going for realism or complexity but managed to have enough of the character of a World War 2 game to not feel overly abstract. It was called Panzer General, and it managed to be a 'casual' wargame with a fairly simple, but solid, tactical system. Back in the mid-1990s, SSI came out with a turn-based strategy game that's considered a classic of the genre.

Panzer general major victory conditions