When I run the game on my 4:3 monitor I have only one resolution mode available in game configuration popup window and the game has badly stretched UI in it - so badly I can't play it at all. I was looking for some solutions but found no answer to my problem - until I found one myself.

The only answer is to play the game in a window but it is still needed do some preparations first to get good final result. Game was created with Unity engine and Unity allows some command line parameters, so here are 5 steps to set this all properly:

1) edit Paper Sorcerer desktop shortcut properties
2) set shortcut target: "<directory>\PaperSorcererPC.exe" -screen-width XXX -screen-height YYY
- where XXX and YYY are selected from any 16:9 resolutions such as: 1280x720, 1366x768, 1600x900, 1920x1080, etc.
- note: you can set any other parameters but UI can be stretched and/or look bad
3) start the game and tick "Windowed" box in game configuration popup window - resolution parameter will not matter
4) game will start in a proper 16:9 window
5) enjoy the game :)

Reference: http://docs.unity3d.com/Manual/CommandLineArguments.html

Update: I've just finished the game myself with this shortcut properties edit and haven't encountered any visible problems.