Right click on Dungeon Siege 2 in the left list of your steam library, select Properties->General->Set Launch Options and paste the following line

However there is a simple fix to start the game. Here it is again, a bit reedited:Īfter a fresh install the game cannot be played in an up to date Windows 10.

My first comment on reddit was about this, but it was removed because I had just made my account.