So our game has this scale feature to fit screensizes of various resolutions. We mainly tested this on 1366x768(mine) and 1920x1080(@Diptoman 's) screens.

At first, we had trouble deciding the resolution of our game. It was a choice between 400x224 or 608x336 (our tiles are 16x16, had to be a multiple of that, and as close to 16:9 as possible).

Dipto went with 608x336 at first - it gave us a larger playing area, and we could scale it 2x and 3x to fit both screen sizes reasonably well. However, I felt that it was undermining the retro feel that I was going for in the art too much. The smaller 400px resolution would give us a smaller play area but improved the simplicity of both the graphics and gameplay(my main reason was the graphics, since I was in charge of the art), but it would also prevent the levels from getting too big and complicated(which I swear @Diptoman does every single time).

So here's what I did - I sneakily made the first few levels and menu in 400x224 while Diptoman was sleeping, ahahahaha(we're on almost opposite timezones). And...well, he was okay with that after seeing how well it worked.

On to the main problem - Construct 2 has this really awesome integer-multiple scaling that allows pixel art to scale automatically with the screen size. No such thing in Game Maker Studio, unfortunately, so I had to nag Dipto a bit for this and had him spend some time programming it - but in the end it turned out very good. One more advantage of the smaller 400px size was that non-interger scaling didn't break it much - it looked reasonably good even in fullscreen, on both resolutions. In contrast, the 600px area was not working nicely in fullscreen non-integer scaling modes.

You can check out our game here, and tell us what you think!