256 = usually for palette ops (fades and color cycles) and as a warning measure about performance since ISA video was still in wide use in the mid 90s. Another about performance is because video cards had the memory to buffer 640x480x256 in that time.

16-bit = usually for early 3d acceleration that only obeys that color depth ever *cough*3dfx*cough*, but also because of artistic choices of being free from the restrictions of indexed color. 32-bit was still heavy to deal with in this period. Multiplatform console ports will favor this for less visual compromise (i.e. Abe's Oddysee, Tunnel B1)

The demand for desktop change's usually about Windows 95 RTM's limitations of not having the ability to do so without restarting (for those who didn't get QuickRes or have OSR2)

Besides the warnings, what use cases are there where not switching to 256 colors would create a problem. I've always ignored this message and couldn't see a difference, but this was some time ago and my sample size was limited.

Maybe this is more of a generic warning that would impact some manufacturers differently, like maybe 3dfx cards?

My curiosity is to find examples where disobeying this advice causes problems, and identifying why this occurs exactly.

Try to play SimCity 2000 Windows in 16-bit color, and your road's cars will stop and your city will animate less.

This isn't just Windows either. MacOS's also got a few of these (and can be way more fussy about it, but at least you can switch depth on demand without restarting).

WinDid early win95 really lack API to query available modes and to change them?
I dont know about warnings, but there are games that will simply refuse to work if desktop mode is not the one they like. Afaik Jagged Alliance 2 absolutely required 16 bit color depth to work in Windowed mode.

Kahenraz wrote on 2022-06-13, 20:35:

I've noticed that there are some games which absolutely demand that you change the desktop resolution before it will run. This is strange, as sometimes the game will be running in fullscreen exclusive mode where they could have chosen the color depth without my intervention. Moto Racer, for example is an early DirectX title (DX3 or 5) and demands 16-bit.

There are also other games which will allow you to use a higher bit depth, but warn you that the game will look its best in 256 color model, such as Earthsiege 2.

What is the reason why games demand this?

I also noticed that oftentimes 16 bit would work anyway. Maybe some games just wanted to make sure you weren't in 16 color mode, and instead of checking for 256 colors or higher, just checked that your depth was exactly 256 colors. 16 color mode is much different because of planar video memory. In fact, because it apparently scrapes video memory, the VNC server refuses to run if you're in 16 color mode.

rasz_pl wrote on 2022-06-14, 21:42:

Win early win95 really lack API to query available modes and to change them?

If they were using GDI as their draw surface, then this would make sense. Even once they migrated to DirectDraw, I can imagine that the code to query the display could have been recycled from that.

GDI has the ability to transparently translate from one format to another, though it can come at cost of severe performance penalty and especially on older hardware. It probably is one reason why games want you to switch to 256 colors that they natively render in etc. as it made sense at the time. Once the hardware is fast enough (i.e PIII) it stops mattering too much, the coversion operation CPU will do on top won't be a significant amount of time over what the game did to render its frame.