I've added a whole bunch of improvements over the last few days.

• the UI now scales according to screen size (was a little awkward as I am using px in CSS)
• Ghouls can now be part of the opponents forces (male and female versions)
• Large skeleton monsters (Skelhor)
• Blood beings (Warbl)
• healers can be upgraded to superior, they clean out dead bodies
• projectiles are now visualized with images instead of rectangles
• switched all music to .ogg (mp3 could cause license issues)
• added sounds to the humans and skeletons, still a lot of sounds missing
• sound volume control
• fixed building placement
• fixed unit selection (click position should be more accurate)
• pixelated main screen, win screen + game over screen
• lots more, can't remember