The playkeepout online game.

This online game is an action-packed WebGL adventure playable for free in your browser.
You need to explore the dungeon, fight monsters and unlock epic weapons .
All this must be collected and completed in the course of 16 rounds online.
The game is fun and keeps you connected.

The Spelunky game .

If you liked old games like old Rick Dangerous, then here's another game named SPELUNKY.
The team development come with this intro:
"Legends speak of a Colossal Cave that extends deep underground, so twisted by time that its passages shift like the sand under which it lies... the Cave is said to be filled with fabulous treasures, but also incredible danger!"
The character of the game has a rope and whip that you can use to explore different areas of the game.
The keys Read about this game here.

News: 0 A.D. Alpha 22 Venustas.

The game named 0 A.D. is free for Windows, Linux and Mac OS X.
If you area a developer then you can redistribute the game and modify it freely as long as you abide by the GPL or you can even use parts of the art and sound for your own projects as long as you abide by CC BY-SA.

 The new features from development team :

• Remake of many models, animations and textures, two new music tracks 
• Configuration-free Multiplayer Hosting 
• Capture the Relic Gamemode 
• Aura and Heal Range Visualization 
• Twelve new maps, including scripted enemies, rising water and a tutorial 
• Espionage Technology, Team Bonuses and Hero Auras 
• Petra AI Diplomacy and Attack Strategies 
• Summary Screen Graphs 
• Cinema Path Editing 
• Buddy System

Tangram - an open-source map renderer.

Tangram is an open-source map renderer designed to animated shaders, 3D buildings, and dynamic filtering can be combined to produce effects normally seen only in science fiction.
The Tangram Play is an interactive text editor for creating maps using Mapzen’s Tangram rendering engine.
 Also, you can write and edit map styles and preview the changes live in the web browser.