Based on the list of Contenders that your looking at it seems like your gravitating toward lesser known text/graphic adventures and turn based strategy titles with sci-fi themes.
As the usual titles like Snatcher & Policenauts have already been mentioned.. I'll try to think a little outside of the main stream..
How about The Hybrid Front (GEN)
A translation is in the works, but not available yet as far as I know. It's basically a tactical turn based strategy game similar to Advanced Wars, or the Panzer General games as it uses hex based tiles. It looks pretty interesting but it's very text heavy so you might need to just keep an eye on the translation project for now.Starflight ( Gen )
One of EA's early ports to the Sega Genesis. This is a sandbox space sim that will have you assembling a crew, outfitting your ship and doing a lot of resource collection to build up your equipment so you can explore further. The main story is a mystery that unfolds as you find relics of the past and try to stop a galaxy threatening phenomenon. Its well off the beat'n path, but it's sci-fi and I enjoyed it many years ago.Frontier: Elite 2
: (Multiplatform - DOS/C64>AT8bit -
The follow up to the original Elite that has spawned the more recent Elite Dangerous. If you enjoyed Star Cruzer you might enjoy this title as well. It's got a bit of a learning curve but there are a number of tutorial vids for this game on Youtube to help you get started. Star Cruiser II: The Odysseus Project ( PC-98)
The English translation is here on Romhacking.net but I have zero experience with PC-98 emulation so I've never tried it myself. Still the videos of people playing it shows it's got a nicer frame rate than the original running on the Mega Drive.Gateway
( AKA: Frederik Pohl's Gateway
A text parser/ Graphic adventure that can be played with a mouse & keyboard. Based on a series of semi-famous sci-fi novels. You play the role of a lucky guy that wins a lottery ticket to be a "prospector". Basically abandoned alien tech is found on mars, which leads to an abandoned alien space station in our solar system. We can't figure out how the tech works exactly but it's something like a mix of Star Gate and Contact where you can type in some rune / glyphs and let the alien pod flash you to places unknown. Some folks just go on a Jodi Foster / Contact ride and see stars and comets and such.. others never come back.. Lucky few land at abandoned alien worlds and sell the tech to the mega corps and retire filthy rich.. but what caused the advanced alien race to disappear...
There's also a sequel Gateway 2
.Super Robot Taisen Gaiden: Masou Kishin - The Lord of Elemental (SNES)
I haven't played too much of it, but it seems to be turn based tactics strategy game kinda like Front mission but with a more Gundam style to it.. Shin Megami Tensei: Strange Journey (DS)
Star Cruiser is kinda like a sci-fi dungeon crawler... and this is the first thing that jumps to mind when I think Sci-fi Dungeon crawling... as a shin megami game it's of course going to involve demons, but at least it's not set in another Japanese "Saved by the Bell meets demons" setting.
(on a side note - Someone should make a Saved by the Bell vs Demon parody game.
I'm sure I could probably think of some more oddities if you want but that should be a good start.