Ok, I just checked the demo (it's totally unplayable on my system), and I can confirm that all widescreen resolutions are supported natively. But you missed something in the cut-scenes section. The demo has an FMV, and you're supposed to show comparison shots for that. I did it for you this time.
1024x768
1280x800
Based on these screenshots, it looks like widescreen is slightly anamorphic *and* slightly hor +. The black bars on the top and bottom recede some but not as much as they would if it was completely anamorphic, and the picture expands some on the side. So I made a composite picture to show what's going on. The widescreen shot is black and white, and the 4:3 shot is in color, placed on top of it.
This is an unusual solution, but I can't find fault in it. So I'll just grade it as if it were anamorphic.
==Grading==
Calculated grade: B
Potential grade: Certified
Major unresolved issues:
Does the full version have any singleplayer anomalies?
Minor unresolved issues:
None
Cranky's coverage estimate: 88.5%