Okay, I checked the games:
- Colossal Cave seems to use stdin, which is not properly supported in rpix86. Fixing this has been in my TODO list for years, but since there are so few games that actually use stdin within the game I have not yet gotten around to it.
- Drugwars probably uses BCD functions, which in rpix86 do not work quite right because of the lack of support for Auxiliary Carry CPU flag. I did not get the exact same error as you, I got "String formula too complex", which is probably caused by the same thing.
- The NFL game does not work on my PC in DOSBox either, it complains about a missing file pdb.nfl (same as what it says in rpix86 for me). This might be caused by a broken or incomplete archive.
So, sorry, looks like these games will not work in rpix86 at least for a while. Please try some newer games instead.