Thank or blame XKCD with
the most recent comic (as of this post), but after sitting for months on what I'm convinced to be the answer, I just joined to answer this. I don't know if the OP found the answer somewhere else in the 4 years, but since this thread shows up at #2 on Google for 'lander windows 3.1', it might help others and prevent a similar situation as that illustrated by XKCD, although #1 in that search offers the same answer I'm about to give.
I believe the Lunar Lander game described by the OP is none other than Lander, by George Moromisato.
I'll just point out a few differences from the descriptions Darg posted...
it seemed very technical with the readouts along the top left of the screen.
The readouts are actually at the top-right. I assume it was just a mistake.
And yea it was black and white.
It wasn't entirely black and white, the lander had color. Then again, I haven't seen v1.0 which could've had a B&W lander.
Everything else is exactly as described.
I have v1.1 - v1.3 available on my website at
http://pilot51.com/wiki/Lander (this is #4 in the search)
Earlier this year with permission from George, I ported it to Android and it's available for free on the Android Market at
http://market.android.com/details?id=com.pilot51.lander (
info/changelog)
I also have a Java port currently in alpha, playable in your browser, at
http://pilot51.com/lander/LanderApplet.htm (
info/changelog)
Oh, and if anyone has a problem with me reviving old threads or posting so many links, I'm sorry, but I felt it was necessary.