> The thing Wolf linked to regarding OpenGL 2.1 support
> concerned the Gallium i915 driver, not the Mesa i915 driver.

Actually, it concerns both drivers. The Gallium driver (i915g) got OpenGL 2.1 support in 2012 (see 1st link in comment #21). A year later in 2013, the way this support was added to the Gallium driver (shader emulating sRGB texture support) was replicated for Intel's DRI driver (i915c) (see 2nd link in comment #21). The OpenGL 2.1 mode of the i915c driver was the default in Mesa until 2017, when the driver was reverted to default to OpenGL 1.4 again because of bad performance with certain applications like Chrome/Chromium and Wine. To keep compatibility with OpenGL 2.0+ games/applications, the mode can simply be changed to OpenGL 2.1 again in the Mesa DRI configuration (see 3rd link in comment #21). The mode can even be set in an app-specific way, so that each software gets the mode it requires or works best in without having to reboot.

https://www.phoronix.com/news/Mesa-i915-OpenGL-2-Drop
https://www.phoronix.com/news/OpenGL-1.4-i915-Now-Default

> I think most - if not all - Linux distributions use the regular Mesa i915
> driver, as that is what Intel supports and, again don't quote me on this,
> the i915g driver is mainly used in ChromeOS, by Google.

As of Mesa v22 (March 2022), all non-Gallium drivers got removed from Mesa, which means the i915c DRI driver got replaced by the i915g Gallium driver for good. This will propagate to all Linux distributions with adoption of Mesa v22+.

https://www.phoronix.com/news/Mesa-Classic-Retired

Quote:

Only that construction trucks now help each other automatically if they are in range of each other, the beta and gamma base missions were added to the timeline of the story game, there are now algorithmically generated random skirmish maps and scavenger bases can be made ultra-difficult during skirmishes also. The replayability has nearly tripled since 2015!

We're lucky it still works on one core! I play on the OpenGL 3.3 driver on my 2014-vintage 3rd gen i7 running Linux using a business grade ATI Radeon card. If it doesn't work on MorphOS, it'll be worth an upgrade. My G4 Mac Mini might not handle it but a RasPi 4 class system should be able to.