Here are a few other publishers I found while going through a computer magazine

Tri Synergy Inc.
Strategy First

Summitsoft seems to lean into the RPG catagory more

Strategy First I support a little bit because they Re-released some Sir-Tech programs

The others I never heard of.

Zagreus sits inside your head Zagreus lives among the dead Zagreus sees you in your bed and eats you when you're sleeping Zagreus at the end of days Zagreus lies all other ways Zagreus comes when times a maze and all of history is weeping