There’s no difference between scaling the graphics and running at a lower screen resolution so that it fits the entire screen, so I can’t see what you’re worrying about.
If your graphics look rubbish scaled up, then they look rubbish already! If scaled up, at least there’s the opportunity that you might use an intelligent scaling that makes them look more attractive…
Also, why on earth would it slow things down?
I found the game Freerail on your website. That’s pretty nicely done. I saw they ask first which resolution the game should run at! Maybe you are right, I should go for that. Maybe allow windowed mode as well!
-moving the main window when the cursor is in the border-> good idea but you must “aim” if you want to do that and that’s really annoying(you must move the cursor at a certain position, it’s not like you’d simpily add to move the cursor all the way on the border of the screen) plus there is a short delay before it start moving
-when going to option and go back-> the screen is not where it was before going to the option menu
-the screen is not on the base in the beginning
-when you make “end game” you go back to the login screen
-no queue to automaticly build several things
-units move too slowly!