There's a way to automatically switch your resolution once you start the game.
Get
Display Changer from the
12noon site (
direct download).
You should set your game to fullscreen.
Now look in your Start Menu under "Programs", there should be a shortcut called "Display Changer 1024x768" or "Display Changer (64-bit) 1024x768" if you took the x64 version.
Copy it to your desktop.
Rename it to "Machinarium (custom mode)" or anything you like, right-click > Properties.
Go to the Tab "Shortcut" > Field "Target".
There are already "-width=1024 -height=768" appended at the end. Change it to "-width=1280 -height=800".
Directly behind append the path to your "Machinarium.exe" e.g. : '-width=1280 -height=800 "C:\Program Files\Machinarium\Machinarium.exe"' or relative '-width=1280 -height=800 ..\Machinarium\Machinarium.exe' (if your Machinarium Folder resides in the folder above the "dc64.exe" or "dc.exe".
Once done click ok and start your game with this Shortcut.
After closing the game screen returns back to initial res
EDIT: If you get a message saying something about settings, you can add "-quiet" as parameter to not display any messages.