Started the game once, and 2560x1440 was now selectable from the ingame menu, as there weren't than many other resolutions to choose from. Exit the game and delete the wrapper files, the game should now be in 2560x1440 or any other resolutions you selected.
There is probably a better way to do it, but why bother if this method works
On the third map or so the game would CTD for me. An NPC is supposed to trigger a level screen when you talk to him again, but for me this didn't happen. Went ahead and cleared the map to see if maybe I missed something, after I did that the game would just crash every time I talked to him. I had to replay the level from an autosave making sure I cleared the map before talking to him for the next level to load properly. So save file corruption is something to be aware of I guess.