My second game built in JavaScript Canvas (HTML5). It's a side-scroller with building elements and destructible terrain. Like a super-simple Terraria. It features:

• Randomly generated level with underground caves and lakes
• Fully-destructible terrain
• Flowing water
• Dynamic and local lighting
• Day/night cycle with night-spawning enemies
• Buildable terrain blocks, including platforms
• Different weapons, including explosive weapons that destroy terrain

You can play it below, or open it in a new window by clicking here (can prevent some text highlighting issues and issues with the mouse scroll). It requires a modern browser to play and generally runs the fastest in Chrome.