Well, I have a little fixation to try to make my projects to work and look great regardless the resolution (I try to make my games compatible from 480p to 1080p). I want to have one universal game build of the game.
The latest C2 addition TileMap is great except one problem (for me at least): does not work well with downscaleing. Not a problem when games are based on a fixed resolution, but if you want to support more resolutions you will have to use upscaling (since downscaling create seams) and the images will look blurry or pixelated with the current sampling (point and linear).
Thanks to anata for pointing out a great solution that is also used in old console emulators <img src="smileys/smiley2.gif" border="0" align="middle">
<img src="http://s22.postimg.org/zcnnrrypp/original1x.png" border="0">
<img src="http://s22.postimg.org/r8fjn1cap/hq2x.png" border="0">
<img src="http://s22.postimg.org/y05ypw1a9/hq3x.png" border="0">
<img src="http://s22.postimg.org/uupydf81t/hq4x.png" border="0">
Comparison of different Pixel Scalings
Pixel Art Scaling Algorithms - Wiki
hqx - Wiki
js-hqx was already implemented in another HTML5 game engine and works well.