Link as many bordering countries as possible (entry for the 10k Apart 2016).
Play the game.
Buttons are heavy things. Stick 100 of them on a page and your 10k budget is out of the window. Minimizing HTML helps a little. But adding an .htaccess file with compression is bees knees.
SVG's are lovely, but not easy. Changing the colour of an SVG, made up of different paths with a mix of strokes and fills, and added as a background image is tricky. You can do it with mask, but then it doesn't work in IE. Shame.