I myself have played a very fast-paced twitch heavy game for the past couple of years on the computer.
I have a cable connection which is one of the faster methods of data transfer by computer game standards. First I'll break down specifically how the data is handled (specifcally, not technically), then I'll just share some of my experience in playing on servers from diff. places around the World.
So its SSBB online mode, you got Gamer A & B. Depending on where the server is, or where the game is hosted, either gamer A or B will have zero to no lag. If the server or host of the game is elsewhere, like a North America East hotspot with a ton of servers, Gamers A & B will both receive lag proportionate to how far away from the server they are. This scenario would be more ideal as both players have the same disadvantage, however the first scenario would be better in terms of players battling fellow gamers closer to them in their region!
Since I'm from Vermont, California is far away, and since it is far away my lag is higher, too. Servers in New York yield much faster data transfer than servers in California. --->
If the given server/host of the match is so many miles away<-->expect this much lag.
3,000<---> 0.7seconds
2,000<---> 0.5seconds
1,000<---> 0.3ish seconds
<1000 <--->little to no lag.
7,000<---> 1.2 seconds
14,000<---> 2.4 seconds
15,000+<---> horrendous lag (in other words, matches played between players around the world are highly unlikely to work out well)
Don't get me wrong though. Specifcally in the game I play, Jedi Knight: Jedi Academy w/ JA+ 2.4R3 Mod, there are still means of playing with the lag. At the US servers every now and again we get an aussie or two coming in and tearing things up. It just takes a ton of practice vs players in far away places until you learn to cope with the lag and make all your moves a second or two ahead of time.
So, to finish, online capability would be nice, but if you want to play against people from ''Around the world'' keep in mind that it's going to be a ****load more challenging to play those people than the people closer to you!
i hope my response was helpful ^_^