A few months ago I noticed that the latest (last?) versions of Reality Boy and Red Dragon are not available for DOS. I compiled them myself, so, if anyone cares, here they are.
The makefiles were outdated, so I had to modify them to get them to compile (with a lot of warnings, but that’s not my problem). They seem to work fine, but Red Dragon has one problem: if you press Esc to pause emulation, it freezes. I thought the problem is on line 1253 of vb_dsp.c (an infinite loop, even though Allegro does declare the key array as volatile), but commenting it out didn’t help. So, to exit Red Dragon, you can press Ctrl+Break to force it to quit.
BTW, Mednafen is also being ported to DOS, but I don’t know when it will be available (I’m not involved in its development).