Created attachment 143564 [details]
glxinfo

Age of Wonders 3 v1.802 Linux version via STEAM.

Some strange vertical lines can be observed on the Main Menu but otherwise the
game appears to work correctly in all other areas (i.e battles, global map)
https://imgur.com/a/IVqewpN

It should obviously look more like this:
https://i.ytimg.com/vi/L-vPu2aeG2w/maxresdefault.jpg

Ubuntu 18.04 LTS, using oibaf's ppa for the latest Mesa packages.

A search highlighted this previous bug report:
https://bugs.freedesktop.org/show_bug.cgi?id=106531

Running this in a terminal:
MESA_GL_VERSION_OVERRIDE=3.1COMPAT steam steam://226840

Or changing the game's launch options with didn't have any effect:
MESA_GL_VERSION_OVERRIDE=3.1COMPAT %command% 

I've captured an apitrace of the issue but it's a bit screwy when replaying it
- what I see occurs offscreen:
https://drive.google.com/file/d/1cGTjw9qgXzAHXvUr_EfjUvFHSAlfARxi/view?usp=sharing

The playback window can be moved up beyond the limit of the screen by left
clicking on the top left edge and choosing "Move"
Works best if you do that once the Main Menu is loaded.
https://i.imgur.com/pQPdukM.jpg
https://i.imgur.com/xtGD3Vz.jpg