Okay, this is weird.

The game starts up at 800X600 32 bit. It takes up the whole screen.

When I change it to 1280X768 (or whatever that one is) it gets SMALLER.

A bigger resolution results in a smaller image.

Can anyone explain that to me?

I kind of like it full screen (though I thought I wouldn't) so it was a bit disappointing that I couldn't get it to be full screen in a larger resolution (such resulting in a sharper image). I mean, it's definitely a sharper image at the higher resolution, buts it's also a smaller one with lots of black space around it (no it's not windowed, it's just a smaller image in the middle of a black screen at a HIGHER resolution, which makes zero sense to me)

That is normal
Imagine your screen is a 4x4 square grid, each square is 1cm x 1cm. So your screen is 4cm x 4cm
The game's image is a 4x4 square grid too, but it is not measured in cm.
You change your screen resolution so your screen is now a 8x8 square grid. The game's image still fit only 4x4 square grid which is now only 2cm x 2cm. So it is smaller but sharper and have black border.
Hope my answer is what you want to ask and clear enough to understand.

Well, if that's normal, then every other game I play is abnormal.

My screen is 1920X1080. And if I play a game at 800X600, it takes up a very small space in the middle of the screen. If I bump it up to 1280X768, then it takes up an even bigger share of that 1920X1080 screen. And if I bump it up to 1920X1080, it takes up the full screen. But that's windowed mode. If full screen mode, it usually takes up the full screen no matter what the resolution is.

It's worked that way for every game I've come across, except for this one.

But your explanation did open up a possibility that I hadn't thought of before. If the game were running in full screen 800X600, then of course that would take up the whole screen. If, by changing it to another resolution, it reverts from full screen to windowed, THEN it would make sense to have a smaller picture.

So maybe that's what's happening????

Anyone know???

I will say this, if it is reverting to windowed mode when you change resolutions, it doesn't look like what other games look like in windowed mode. Normally in windowed mode when a game's resolution doesn't take up the whole screen, you will see your desktop in the areas not covered by the window. In this case, it never appears to be windowed mode, because the only thing you see around the image is black space. I.E. it appears to be full screen mode.

I'm not particularly tech savvy when it comes to computers and video games, but my dad had an electronic appliance store, and if this has something to do with resolutions, I think I may be able to tell what the problem is.

From my understanding, it has do with the aspect ratio vs. the resolution. Games need to upscale and stretch the image being displayed, and older games (VGA and SVGA) only supported 4:3 aspect ratios. When you up the resolution from 800x600 (4:3 aspect ratio) to 1280x768, you change it to a 5:3 aspect ratio, which is almost impossible to adapt to a 4:3 one -- especially in your case, where your native resolution of 1920x1080 (16:9) is super compatible with every 4:3 ratio, therefore not with 5:3 ones. A 1280x720 resolution, on the other hand, being in 16:9 aspect ratio, is exactly the same as your native ratio, and should run fullscreen without any borders.

The problem, as far as I can see, is that Fallout Tactics is one of those games that uses the odd 5:3 aspect ratio for one of its resolutions, but doesn't fit it to screen because it's only able to do so with 4:3 and 16:9.

I hope this explanation wasn't too confusing, and sorry for not knowing how you'll solve your issue... maybe try a 16:9 aspect ratio resolution, if it gives you that chance (1280x720, for example), or a higher 4:3 resolution (1152x864 or 1024x768). I don't have it installed, so I don't know the resolution options it gives you... :-\

Well, I thought you were onto something, but then discovered I was the one wrong (again).

It's not the resolution I typed above but it's 1024X768, not 1280X768.

There are only two options in the game, well four really because both resolutions can be run at 16bit or 32 bit color, but it's still just two options in game. 800X600 and 1024X768. My brain's not working well enough to know whether or not that's 4:3, but it's darn close I think.

I dunno, I'm not gonna worry about it anymore. When in 800X600 it takes up the full screen, and when in 1024X768 it doesn't, and that's just the way it is I guess.

Yup, 1024x768 is 4:3 aspect ratio. I guess it's just the game being that way, or some thing with your GPU that I'm definitely not knowledgeable enough to help you with... :-\

Sorry, I hope you manage to sort that out.