We have always played One Flag. 2 bases on either side, one flag in the middle. The team to retrieve the flag and get it back to their base wins. You can also have a variation where the team that retrieved the flag has to defend it for a couple of minutes. Whenever we get out we have to go pack to our starting spot (not our base but a place a little bit aways from it for each team) and count 30 seconds and come back in.
Usually we don't have enough markers so some of use have to use makeshift riot shields which makes for an awesome fight, especially on the place on my property.
Just make sure you guys have enough CO2 and/or Air XD