Досбокс порой не панацея. А Семерка сама по себе уже даже через совместимость кучу игр не может запустить. А в окном ты надо прописать режим в файле конфигурации
To change available screen modes, edit "keeperfx.cfg".
Screen mode can be in a form WIDTHxHEIGHTxBPP which defines
fullscreen mode, or WIDTHxHEIGHTwBPP, which defines windowed
mode. When defining windowed mode, the BPP should be equal to
the colour depth on your desktop. It is not recommended to
mix fullscreen and windowed modes in one config file.
There are two lines which define resolutions: 'FRONTEND_RES='
should have exactly 3 parameters and is used in the menu,
while 'INGAME_RES=' can have 1-5 parameters, which define
list of resolutions to switch between in the actual game.
Most stable modes are 640x400 and 640x480. Higher resolutions
may be sometimes unstable, especially in possession.