Games that try to do both SP and MP usually fail lol.
Well I'm saying that with the exception of probably COD series.
But COD only attracts such a large multiplayer crowd because no matter how bad you are at the game, u can still enjoy it.
Definitely put multiplayer. Single player games are one off things. I finished COD6 in like 3 days (not playing it allday obviously, just from when i installed), and got bored and have not touched it since.
I've been playing CSS competitively since 2008 and still do, because the multiplayer is great
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Not saying it's the best game, just what I think.
If you look at Steam Statistics, the top played games are all multiplayer.
1. COD6 - Multiplayer
2. CSS
3. CS1.6
4. TF2
etc
Probably in the first few days of release the SP games would have a bit of playtime.