This isnt the Engine

You're talking more about the game then the actual engine used to create it. Which is why so many other games like secondlife have the same controls, and even look. (like Legend city). Saddly i'm unable to find the game engine anywhere now a days so I cant get you the name or information about it.

This is not a game engine. remove it from the list.

I simply can not understand guys telling Second life is agame engine. Is there any sensible person, who can think of some game level editor, like a game engine?
You can upload your data on their site - what a delight! Nonsence - game engine must aim on game creation - not on adding new modules to existing games. So, please remove this fake "engine from the list.

Is it a game engine?

Second Life is a peristent world that allows users to add their own models, animations, scripts, particles, etc. For those testing out MMOG ideas, or for those tinkering with only the scripting side of an engine, Second Life could be a good fit. i.e. artists, weekend tinkerers, etc. There have been some small to medium size games built inside the world, but it is limiting in the amount of real estate you can use to build a game due to the equation in Second Life that land=money. Could you build an MMORPG like Everquest or WoW in Second Life: theoretically yes; some things would be easier or harder depending on what you are trying to do...

The benefits:
1. MMOG with users that you can test your ideas on.
2. Low cost of entry: (One time fee of $9.95)
3. Bandwidth & servers are maintained for you.
4. Users can upload their own content.
5. All users reside in the same virtual world. (No multiple game realms)
6. Linden Lab deals with server hackers & accounting not you. (Although you may need to deal with people hacking your scripts, content, & your own personal accounting)
6. Server side physics, scripting, animation, etc.
7. You are a part of the Second Life economy and can make real world money.

The limitations are:
1. You don't get the source code and are therefore stuck with what the engine can and can't do.
2. It has to be run on their servers and users must login to a Second Life client. (i.e. no private branding)
3. You are a part of the Second Life economy and can spend real world money. (This can be expensive if you lease a bunch of servers that no one wants to visit.)
4. Users can upload thier own content. (It can be ugly.)
5. Requires broadband access.

It is fairly full featured in what it does allow, when you consider what you can do with other engines without modifying the source. Plus they always seem to be adding new features. They license servers (a.k.a sims) to individuals allowing them to create their own games per se for about the cost of leasing a dedicated web server through web hosts. Seeing how web hosting has grown in the past decade, I can see real potential for Second Life. Because you can spend/make money in Second Life there are some people who make a full-time real world living just making games and content for Second Life. I believe they are the first game to encourage exchange of game money for real money. Because other users can purchase your content and you get paid for how many people visit your land, you can really make a game that pays you with only in game marketing.

For some die hard coders I know, if they didn't write the assembly themselves, they don't consider it a 'real' engine. In fact, that's the case with a lot of developers in general.

IMHO I think the real question is can you make money developing a game with it. With Second Life, the answer is yes. How much money has your engine made you?

Second Life is a valid development platform

While Second Life IS a virtual environment (not a game, per se), its engine is valid as a development platform:

"Second Life is a 3D platform for developers who want to present, promote, and sell their content and applications to a broad online audience within an immersive, shared space.

Unlike other massive multiplayer online experiences, Second Life has few restrictions and provides broad and flexible content authoring experiences for developers interested in building, creating and evolving the world of Second Life.

Second Life provides our expanding developer community with ownership of anything it builds or creates in Second Life. It is yours to sell, trade or monetize within the rapidly increasing population of Second Life Residents."

(source: http://secondlife.com/developers/)

Second Life has had 2 game developer contests and its scripting language is sufficient enough to create complicated enough behavior to warrant Second Life to be classified as a development platform.

http://secondlife.com/developers/features.php for more details on its developmental features.

this should be removed

This is a GAME. NOT a game Engine. It allows users to upload their own artwork, true.. but it has no real business being here, this is a developer related site