I managed to discover this by mistake. I have Windows 7 just in case if it is different for others.

Get in a match. Go to save game screen. You should have a new popup asking you to save a new file. This is when you alt+tab. After alt-tabbing, do not go anywhere else, stay on the game. Save the game or exit save screen. Then what you have is windowed mode game running.

Let me know if this works for you. It managed for me.

Works for me.

Funny thing, I was just coming to the forum to post this, I owned Chaos Overlords back in the day and this is the workaround I discovered (quite by accident) to play in windowed mode.

It's not exactly windowed mode, you can't move the window or anything, it's stuck in the top left of your screen but at least it's not full screen and it shows all the graphics unlike the registry edit way to get windowed mode.

It still acts as if it's full screen and goes back to normal if you alt/tab again so if you're watching YouTube or whatever on a second monitor then get it all set up during the first alt/tab because if you try again you'll have to go through the whole process again for every time.

I just discovered this trick today and came to post it also and saw there was already one up too. After doing it the first time and not knowing what i did, i just played with it until i figured it out.

I am using windows 10 and it works there too.

Thanks for the info. I just wish i had checked here 2 months ago. Would have saved some hassle

It's something to do with certain games and Windows OS behavior. This is how I play Civilization 3 in a window too.

There's no way it works in Windows 10 since Chaos Overlords won't even start in Windows 10.

It won't start in windows 10? So you mean this whole time I've been imagining myself playing the game? No wonder I win so much. Geez, I need to see a therepist who can prescribe me some strong meds. I cant believe Iv'e been just imagining playing this game for 2 years on windows 10.

OOOOORRR...........a more likely scenario is that you shouldnt open your mouth anymore because you clearly have no idea what you are talking about. but thanks anyway for that argumentative and non-helpful addition of gibberish.

What a stupidly arrogant answer. If you really think Chaos Overlords works flawlessy in Windows 10 you couldn't be more mistaken. I confess i was wrong about the game not starting up at all but at the same many of the tiles in Chaos Overlords shows up as blanks so it's not working as it should be.

There's a reason why it says on the store page it's only compatible with Windows 7.

you really should stop talking. you are making yourself look bad. As you are not here playing the game on my computer.....how could you possibly tell me how the game runs on MY system?
yes, it does work flawlessly. just because you cant figure out how to get it to run properly, doesnt mean that everyone is the same. the blank white boxes is a fixable problem.
how arrogant of you to think that just because you lack the ability to problem solve, everyone else must as well.

Either you don't know which Windows you are running or you're running a non-GOG version or running it in a virtual environment. If there really were a fix for Chaos Overlords under Windows 10 GOG would have updated it long time ago.

It seems you're the only one who got it working on Win 10 which must make you some sort of Wizard. Go ahead and tell GOG about your magical fix.

I'm not anywhere near the first one to figure it out. many have fixed this problem. technically, it breaks a rule so cannot be sanctioned or posted anymore.
to continue to argue like you have about this makes you (in all seriousness) one of the biggest morons ive ever had to deal with.
you are one of those types that needs to be right and thinks they know everything about every subject, even when you are clueless.

you truely look like an aweful, arrogant person by continuing to tell me what my computer is doing lol. im stunned by your incompetence. please for the love of god, stop proving your stupidity, just keep your teeth together, and go play your game. smdh

go into the data file and remove the px16 folder. keep the folder, just remove it from the data folder. you'll have to play with your own settings from there.
the white box problem is just a color issue
although i cant tell you exactly what I did to fix the problem, you can probably figure it out from there.
except you klappis....since you are stuck on believing that you are the "almighty know all" and no one could possibly fix the problem