Sometimes with the RO 3.3 mod I just wanted a quick game with my favorite weapon, on my favorite map, without bothering to find a server. And I still wanted a real challenge.
So what I did was to load up bots, then play with "no respawns" - if you die, the map is over. You gotta reload the map and start again.
Try to survive 20 minutes against the AI without getting yourself killed, and you will *maybe* find it a bit more realistic than the standard "go cap, get shot, respawn" you find on most servers.
In that respect, it's a good offline game - especially when you play it without HUD (gets rid of chat and most important, dead text messages).
Further, what I did was to sort the avalable maps by date and play trough the whole "eastern campaign" each map with only one "live". That's single player enough for me.
Of course some things are missing - but some things are missing from the online play too.