Quoting Sweet-Zombie-Jesus,
Download 2.58 Mb/s
Upload 0.32 Mb/s
Ping 63 ms
Basically the MOST your modem can push (from the speedtest you showed) is ...
Download : 300 KB/sec
Upload : 40 KB/sec
Now what is killing you is your upload speed. I think you would be safe for 2v2 games and 3v3. But personally i think anything higher than a 3v3 you will start to really strain your connection (on the upload part ... which is needed) and therefor you start to lag like crazy.
Below i explain why you can play "All other games" and not Demigod so wonderfully.
(My connection)
Yeah ur connection is really that bad. You barley pull 0.3 on the upload. Hence why you can't play.
WoW and stuff (Ur x-box / ps3 games / other Online games) uses something we like to call "Client-Server". Therefor the server just keeps up-to-date with everyone and just sends you nice little info about whats going on.
In Demigod its p2p (peer-to-peer) and it doesn't work this way. YOU have to tell everyone in game what is going on just like they have to tell you everything going on with them (See if you think about it ... its pretty crazy huh? ALOT more info going around).
So think of it this way ...
2v2 - You are DLing from 3 people... their clients are telling you what is going on and you are telling them what is going on (so you are uploading to 3 people as well).
3v3 - Gets a little more intense! You are now DLing info from 5 people at a time while uploading your info to 5 different people.
5v5 - Now you are DLing from 9 people and uploading to 9 people.
See the difference? In WoW / "Other Games" (First-Person shooters ... any xbox/ps3 games) you and the server talk ... thats it. The server updates you what those thousands of kids are doing (On WoW) or the other 32 people (on a first-person shooter) ... your not having to talk and upload what your doing to every single person. Just the server and it takes care of it.
So thats the difference. Welcome to p2p. Its your connection...