Engine Suggestions

Hi, I'm just looking for some help picking an engine that'd be right for me. I don't want to give away to much about my project but let me share some basic features:

• first-person online action game
  
• focus on melee combat (with some ranged)
  
• large scale maps
  
• hunger system
  
• AI "monsters"
  
• "RPG style" loot/equipment
  
• matchmaking
  
  I'm thinking possibly Unity, since that seems like the big engine floating around for indie developers as of late. But the Source Engine was also considered, though I've heard nasty things about trying to mix large maps and Source together. If you know of any other, better, engines for this kind of project please tell me.
  
  I'm just curious to know your opinions on which engine would be the most effective, cheap, and easy to use when it comes to a project like this. If anybody has any recommendations and suggestions, I'm all ears.
  
  Carnifex
  

If you want easy to use then i'd say: Unity or UDK.

Unity can be used for free (with limited features) as long as you had less than $100k turnover last year.
UDK can be used for free as long as you don't do it commercially. (no feature restrictions AFAIK)

Unity Pro licenses start at $1500 per seat. (iOS support is an extra $1500, Android yet another $1500)
UDK commercial licenses cost $99 + 25% of revenue above $50k or $2500 per seat (iOS support is included, Android support isn't an option (requires a far more expensive UE3 license))

You have to implement most of the high level features you want yourself either way (and everything you listed, except large scale maps are high level features) large scale maps can be difficult if the engine doesn't support asset streaming but most modern engines can handle that. (Unity supports it atleast, i havn't looked at UDK but i'd be surprised if it didn't support it)

If you want easy to use then i'd say: Unity or UDK.

Unity can be used for free (with limited features) as long as you had less than $100k turnover last year.
UDK can be used for free as long as you don't do it commercially. (no feature restrictions AFAIK)

Unity Pro licenses start at $1500 per seat. (iOS support is an extra $1500, Android yet another $1500)
UDK commercial licenses cost $99 + 25% of revenue above $50k or $2500 per seat (iOS support is included, Android support isn't an option (requires a far more expensive UE3 license))

You have to implement most of the high level features you want yourself either way (and everything you listed, except large scale maps are high level features) large scale maps can be difficult if the engine doesn't support asset streaming but most modern engines can handle that. (Unity supports it atleast, i havn't looked at UDK but i'd be surprised if it didn't support it)

UDK completely slipped my memory, thanks. I'm giving it a look, and it might be just what I need, since I don't think there's any doubt that UDK is a good engine for online shooters. Sadly I won't really be able to dive into it until I get my new rig built, since this old machine has trouble running modern 3D games.

Thanks a lot though, you've been a big help.