Space Commander 
An online space war game in which each player starts with his own planet. The first important step which should then be taken is to build facilities including energy plants and mines to collect raw materials. This material can then develop new buildings, including shipyards for space vehicles, ships and weapons to develop defenses [...]

 
Gangster World

This is a Gangster Multiplayer Online Game with many unique options. You start as an ordinary laborer and you end up in the world of the Mafia. You will be asked to do crimes muscles to grow in the gym. with each rank you will get more benefits, you can buy new weapons, new [...]

DimensioneX Multiplayer Game Engine is an interactive multimedia free open source for developing and running adventure games. 
If you have ever dreamt of developing a video game then this tool is just for you. It is easy, quick, flexible and robust, hence a beginner can also be comfortable in developing a web based interactive game with characters [...]

The Nowhere Else and Beyond Game Engine
 The Nowhere Else and Beyond (NEaB) engine is a fully  customizable 2D game engine based on the hugely popular MMORPG  of the same name. The distinctive, and unique, map system allows you  to create a variety of different game situations and the art provided  with the engine is [...]

Deathray Games released one of their games under the creative commons license.
It is a very simplistic, one-player, fantasy hack’n’slash browser game which leaves a lot to do with it.
You can easy adopt it to have it build in other game engines, make it multi player whatever as long you follow the creative commons license.

Game: http://deathraygames.com/play-online/drg/greenhydra/index.html
Download: http://deathraygames.com/play-online/drg/greenhydra/archives/LOGH_v1.zip
Deathray the [...]

The Horizons Game Engine
Our philosophy
The Horizons Game Engine (HGE) is intended to meet three essential needs of browser game owners and developers.

Secure code!
HGE is built from the ground up with security in mind. We’ve worked on many games and see just about every security hole there is. HGE has tons of built in security precautions. [...]

The Gangster legends engine is as it is, the developers deprecated the further deveolopment of this engine.
### General Information ###
Gangster Legends: Source is a text-based MMO gangster game written in php. The base of GL: Source is the v0,75 script that has been available for download for a while now. We decided to [...]

Pro Version adds NVIDIA PhysX
New Collision Library Incorporated 

We have recently begun the incorporation of the NVIDIA PhysX Physics library into Realm Crafter Professional. It will replace the current collision engine to provide faster and more reliable collision detection. Integrating PhysX opens many new doors for the future of Realm Crafter; such as the use of [...]

The Dragon Knight game engine is an online game system created by Jamin Seven. It is an RPG-style game in which characters explore the map, fight monsters, gain experience and buy items, among other things. It is written in PHP4, with a MySQL database backend. While it was originally envisioned as a medieval/fantasy type game [...]

Deploying your Game
So, your game is complete and ready for the masses, but how do you get it to them? That’s where deployment comes in.
The first step in deployment is hosting your game, later we will focus on exposure in other words advertising your game (free and paid methods).
Hosting Your Game
Cost
Cost is, as it is [...]