This great indie game's options screen only allow setting the resolution up to 1080p, but the engine can go much higher! Here's how.

1. Go to the following folder
   "%USERPROFILE%\Documents\Documents\ConstantC_Saves\"
   
2. Open gameSetting.txt with notepad or a similar text editor
   
3. Under the "Environment" heading, change Screen_Width and Screen_Height as follows:
   "Screen_Width":3840,
   "Screen_Height":2160
   
4. Save the file, launch the game, enjoy! The game now looks much sharper (especially in the cutscenes where there are human characters with more rounded edges).

Note: When setting the resolution like this, THE ZOOM FUNCTION NO LONGER FULLY WORKS. If you hit the Zoom button (either of the increase/decrease zoom buttons), the zoom gets stuck on fully zoomed out and only resetting the level can restore the original zoom. Panning (looking around) still works normally though as do all the menus. Steam Big Picture mode may prevent panning (unknown if this affects the base game already though).

2022-01-01 - V1.0, 1.1 - First release, 1.1 adds information about Steam Big Picture mode