Map control and res-denial
This is a pretty conservative strategy that is possible in 2.0, partially due to the effectiveness of turrets. The goal is to control the map via lockdowns of two chokepoint and obtain a 5/2 advantage in RT's, allowing you to out-tech the Aliens. You also use the Map to your advantage, holding easily defendable areas that will give you advance warning of any incoming. This strategy will only work if the Aliens DON'T start in Cargo, which should be 2/3 of the time.Starting out
You want pretty much the whole team to immediatly rush off to Generator Room. Leave 1 or 2 Marines in Base to build 2 IP's and an Armory. Once you secure Generator you drop a TF there (on the Viaduct side of the hole), an RT and 2 or 3 Turrets. Keep the majority of the team in Generator and have one guy run around to cap Cargo and Ventilation chamber, leave Miasma open for now. Have the guy who capped Cargo return to base and let him know he is now responsible for the cargo area. Give him a pack of mines and send him back, he will need a friend to boost him into the vent in Cargo, where he will place the mines.
Now you have Generator somewhat secure and Cargo vent is sealed off. Leave some guards in Gen and make sure they keep the elevator UP at all times. As long as the elevator is UP you will get advance warning on all attacks. Now send a big group over to the Quad Lift area (at least half the team, 1 guy is busy in Cargo and 2 can hold Gen). Put up a new TF between the Quad Elevator and the Foreboding Elevator. Don't spare expense on the turrets. You want at least 6-8 Turrets in this area, covering the corridor leading from Quad to Miasma and the one leading from Foreboding to MS. Once again, get a guy to go in the vent (leading from Foreboding to MS) and place mines. Cap MiasmaThe Mid Game
Now the Aliens should have 5 nodes and possibly a second hive going up. Time to do something about that. Upgrade the TF in Generator. You have 5 nodes now and resources should be coming in rather quickly. If your Marines follow orders the K:D ratio will be excellent as well, meaning more resources for you. This is when you start teching up. Observatory and Amrslab should be dropped, and Armory upgraded. You want to make sure you tech a lot faster then the Aliens though, so place 4 sieges in Generator room. 2 to hit Ominus Kismet and 2 to hit Viaduct West. You should keep half your team in Gen and the other half in Quad/Foreboding. Get Phasegates up to these areas and keep putting mines in the two vents.
Once you start sieging Ominus and Viaduct West, it's a good opportunity to have your team at Quad move into Foreboding and attack that RT. Aliens will most likely be running to the ones being attacked by Gen, leaving your team time enough to take down the Foreboding RT. Don't be tempted to cap it, just destroy it and back off.Late Game
I don't like taking chances if I don't have to, so I will tech up to lvl3/3 and HA/JP before moving out. Holding the two chokepoints is really easy as long as you keep the elevators UP. You will get plenty of warning and will be able to be there with a lot of people, and with plenty of turrets to back you up. This should ensure an outstanding K:D ratio and very little RFK for the alien who are feeding off 2 nodes. So you have all the time in the world to tech up. I like to go for an elegant finish, here's my suggestion:
Siege out Red Room if you have to. Have Two JP-ers stay in Gen Room and outfit the rest of the team with HA. All the HA's Phase to Quad and start moving towards powersilo (cap the node in Foreboding) and making lots of noise. As soon as they are spotted (which should be pretty soon) the JP-ers go for Red Room. Get the HA's an Armory outside Power Silo and tell them to start taking it out while you build up to siege Viaduct from Red Room. With a bit of luck and timing both hives should go down within one minute of eachother.Possible problems
Generator Room - The main problem here is a skulk getting up on the balcony and going gorge before you have GL's. He can then proceed to bilebomb everything in there while being extremely hard to kill. This is best stopped by having your guards there build a human tower to get up there and build a turret (or 2), during one of the calm moments (remember, the elevator going down will always give you warning).
Behind the lines - You aren't building any defenses elsewhere, so it is important that the ones you have in Gen and Quad are effective. A skulk *will* be able to get through Quad to Miasma by leaping so you either fix this by building a TF around the corner or by having a guard there all the time (I went for the TF, which upset the skulks;)).
Sloppy - Don't get sloppy. Don't let them clear out one of the vents, this will alow them to sneak up the hive. Always keep the vents mined and the chokepoints guarded.
Fades - Fades are the only Aliens that can get past your defense, but don't worry. Once he is behind the lines you will have people hunt him down, and here's the best part, he can't run away since he will be so low on health that the turrets will kill him if he tries to get back to teh alien side. At least this is my experience. Just make sure there's a couple of shotguns on the team.
Peer pressure - Don't let Marines pressure you into wasting your res. This means turning down the Marine that just got into siege position for a hive or capping any other nodes then the 5 on the upper floor. You'll take down the hives when you're ready.Upgrade order
That's the order I prefer when using this strat.Extra Points
You can do these things or not, if the above is done correctly you don't need to but if you have the time and inspiration.
Commando Raids - Send raids into the hives to take out the upgrade chambers. If they are down, the RT. I managed to take out the MC's in PowerSilo and the RT in Viaduct (JP/Shotty got it into the Red and two LMG's rushed in to finish it from above).
Redundant TF's - Having a TF with a Turret guarding the Cargo hive gives you a warm fuzzy feeling of safety. It is possible to place turrets in the Vent, but don't. A lerk can kill them while being out if range of the turret. Having a TF right by the ladder in Miasma is also nice, and will surely annoy the hell out of any skulk that just managed to leap past your farm in Quad.
Armories - It's nice for Marines to have armories. Drop them at all the farms, and also, drop one below the Cargo vent, this will alow the Marine there to go up into the vent without a boost and will allow you to give him mines there.
Electrify Everything - It's nice to have stuff electrified. Since it's usually not cost effective, take this time when you're in control of the game and swimming in res to electrify everything, it will make you feel better.Marines
This is not a boring tactic for Marines. Aliens will constantly be probing your defenses so your guards will most likely be kept busy. They will also experience how easy it is to combat aliens when you are supported by turrets and teammates, and have plenty of warning of the incoming attack (Elevator UP and MT). There's also the mine placement and the hunting down of renegade skulks (or a bold/crazy fade). If things are slow, organise a raid into enemy territory.Map
The red areas are of course the choke points (or Turret Farms if you like), the star shaped symbols are RT's that are to be sieged, the arrow is where your Marines will be moving out (first to kill the RT, then to attack PS when it is time to end it) and the verboten signs are the vents you need to seal off with mines.
This strategy is tried and tested on the CoFR server. It will require teamwork from the Marines to be successful, but what strategy doesn't in 2,0. If you fail to take Generator room on the first push, make one more attempt and then switch strategy if it didn't work.