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[Dave]

Keen Dreams (aka Commander Keen 3.5) (1991) id Software, Inc.
Freeware

Math Rescue (1992) by Apogee Software, Ltd.
Sold here: http://www.3drealms.com/math/index.html

I'll hide the link, btw I still have it to check the other titles.

Edit: I don't have much time in these days.
(Link sent )