Rush rush rush, camp camp camp. That's all this game is. All aliens can do is rush because all marines ever do is camp. I'm going to use Natural Selection as a point of comparison; it's a slightly different game, but it's the only way to get at the nature of this game's many problems. Largely, it's an issue of urgency and a complete inability to meet it should a sense of it exist.
NS propells teams forward by the sense of urgency that's created by the necessity of resource nodes. You camp, you don't get nodes. You don't get nodes, you don't get resources. You don't get resources, you get outpaced by the other team who can afford better species and weapons. Tremulous has none of this. There is absolutely no reason to leave the base as a marine, because you can get kills -and therefore, money- by staying right next to your armory.
There are sub-issues at play here. The first is the magazine size of the default marine weapon; there's no excuse for keeping it that small.
The second is the building system. In NS, commanders push forward slowly by building up areas as the squads go. In Tremulous, not only is the amount of structures extremely limited, the effort needed to move anything is far greater than it's actually worth. To move forward, you'd need to decon something, taking away from base defense, which is bad since it's the only thing that keeps aliens at bay. To build it up, you'd need the entire team with you for cover because it takes so long to actually construct something.
That itself is impossible because the damage models are WAY the fuck off. Every single game, i see Marauders going up against light armor marines and winning. And Marauders come out 2 minutes in. Last night i played a game where a Marauder attacked 4 marines, all of whom concentrated their fire on it, and STILL came out alive because 4 full magazines weren't enough to do anything. Conversely, the Marauder took each marine down with 1 or 2 hits. It's most intuitive for marines to hole up in their base simply for the fact that at no point during the course of the game will they feel like they're capable of doing ANY appreciable damage to targets that are stronger, tougher, and faster than they are. The game teaches them that not even greater numbers matter. They stay in their base because the turrets are more reliable than they could ever be. They learn this from the fact that turrets and long hallways are the ONLY things that give aliens pause.
So, the weapons. Even the shotgun feels like shit. In NS i used to chase fades down with an LMG. I am the epitome of ballsy playing. In Tremulous, there is no, NO reason for me to think i want to be anywhere other than right next to my armory. Personally, nearly every weapon is crippled by ammo capacity. With the sheer amount of firepower it seems like it takes to take anything down, the game constantly shouts at me the notion that i'm either going to be caught during a reload (which takes too fucking long, keeping me next to the armory. Don't cripple the armory, SHORTEN THE DAMNED RELOADS.). If i don't, the max ammo capacity strongly suggests that i'm going to run out by the time i get anywhere from the base. That's IF something doesn't spot me and my squad and take us out in 1 hit each. Worse if FF is on. And unlike NS, there's no commander to drop ammopacks for me. I've gotten basilisks down to near death with the shotgun countless times, but it always manages sto scamper away because of the magazine capacity and the fact that the RoF feels like i'm on a leisurely quail hunt rather than an urgent fight for my life.
No perception of damage dealt, no percievable upgrade structure, no apparent counter to anything, no reason to leave the base. This is made worse by Tremulous' strange lag. Even with 50 ping, i'm never sure how much i have to lead something. THIS IS UNACCEPTABLE when you're trying to pin down a fast-moving alien. Double-fucked if you're trying to do it with a non-hitscan weapon.
The only exception to this is on the Alien side, with the Dretches. What fucking IDIOT came up with the 25 health max? I quit a server and look for another if i'm auto-teamed to Aliens past the first 3 minutes of the round. There's absoultely NO WAY to get the points to evolve into anything. This makes playing pointless, since again, marines have no reason to go anywhere a Dretch would be able to use its abilities. Dretches, at that point, exist only to make marines feel like they're capable of doing something. They're obsolete almost immediately, compared to NS' skulks, which remain viable against everything except bases and heavy armor. NS skulks are valid "resource saving" forms, while Dretches are target practice.
And on that note, please make wall walking more disorienting. I love having that ability completely nullified by the complete impossibility of being able to tell where i'm going, or if the game's going to suddenly decide to toss me off the ceiling for no reason.
But back to the weapons again, on the alien side i find myself sighing every time i come across someone with a batterypack and a lasrifle. The other side of the extreme, a magazine capacity that allows and encourages spray-and-pray spamming. Some of the better weapons, the pulse, flame, and chaingun, are all meant for spamming. Spam creates a guarantee that you're going to take some damage no matter what you do. Spam creates the only viable role a marine can take, which is that of a reinforcement for turrets. More camping follows. The heavy weapons like the Lucifer are the stereotypical "Strong but worthless for CQB" weapons, which also do nothing to encourage people equipped with one to move out. There also aren't really any appreciable structures that a player would instinctively want to use them on either.
Let's move away from that for a minute though. There's the issue of communication. If a team were to make the irrational move of heading out from the base, it's an act that requires a massive amount of coordination because of everything above. This communication is completely unsupported by Tremulous, which doesn't even have hotkey-driven voice macros. That's not even the most important thing though. Voicecomms are. Games like this need built-in voicechat. Period.
So, ultimately, the marine base is the only thing that aliens cant immediately trample over. Because of that, the base is constantly the focus. All the more reason to feel you need to stay in it and help defend. More camping. And thanks to the maps, there are generally only 2 doors into the base, with none of NS' many airducts and tunnels facillitating accesss to the smaller alien species. There's no way to harass the marines into coming OUT of their base in Tremulous. MORE CAMPING.
This game could be fan-fucking-tastic because it eliminates the biggest problem with Natural Selection, which is the commander role. But as it is, playing Tremulous is an unmitigated waste of time. You guys have a lot of work to do. It's time for you to actually start thinking about the structure of the game now that you have the concept.