Strategy

Principal differences between humans and aliens
Dependence on structures Humans require structures to heal and restore Ammunition. Aliens don't. This means the aliens' base is a purely defensive Structure, while the humans' base is both defensive and offensive.

Autonomy vs. teamwork Since they are not tied to the base, aliens can roam the map at will. Therefore, Alien success is more tied to the skill of individual players (sneaking, attacking, ambushing) than an overall coordinated team Strategy.

Teamwork for all!
In Tremulous, it's rare for a single player to kill another single player. Most kills are the result of damage from multiple enemies. This is why Credits & Evos awarded for a kill are distributed between the attackers responsible for the kill.

Strategically, this means that simply damaging enemies is a worthwhile goal (as long as your teammates are helping finish the job). There's no such thing as “kill-stealing”.

Sudden Death
After the game has progressed for a certain time period, “Sudden Death” occurs. At this point, no structures can be built. (NOTE: Depends on the server settings with some servers allowing some structures to be rebuilt) Some possible setups:
 * 1) Default setting (and common on most servers): only buildings which costs 0 build points can be built - it means that you are able to build reactor and repeater (as human) or overmind (as alien)
 * 2) No building of any kind allowed
 * 3) Only non-fortification buildings can be rebuilt. This means that the Build Points of all existing rebuildable structures is totaled at the START of SD and those Build Points can be re-used througout SD. Rebuildable buildings are:
 * Humans: Reactor, Armoury, Medistation, Defense Computer, and Repeater
 * Aliens: Overmind and Booster

Since humans are highly dependent on structures, they are at a severe disadvantage once SD is declared. Some servers have no SD.

Psychological Strategy
To secure ourselves against defeat lies in our own hands, but the opportunity of defeating the enemy is provided by the enemy himself.

- Sun Tzu

The enemy begins with a goal in mind. If that goal is denied enough times (or severely enough), the enemy is discouraged from attempting again. This sounds basic, but it's tougher in practice than in theory. Let's say one player is committed to assault a position, and the other player is committed to defending it. Both players will be distracted by other developments (positive or negative) for their team, and will feel tempted to abandon the post. Since a game is just a game, boredom can also become a temptation - it's not that fun to repeatedly assault or defend one position.

Confusing the enemy
If the enemy's goal is made impossible or irrelevant, the enemy enters a state of confusion, which lasts until another goal is found. Maintaining this state of confusion as long as possible cause the enemy to be ineffective.

Use forward bases, baiting, and counterattacks to keep your enemy on his toes. Sometimes simply wasting time is as valuable as getting kills – distracting an incoming attacker long enough for the rest of your team to react may save your base, even if you die. One of your enemy's main assets is his attention, and if you can draw it from vulnerabilities you will gain a significant advantage.

Attack by stratagem
The rule is, not to besiege walled cities if it can possibly be avoided.

- Sun Tzu

Do not pass up opportunities to end the game quickly in favor of slowly breaking down your enemy and increasing your killcount with “conventional” attacks.

For example, sometimes unskilled builders make the mistake of concentrating all defenses in easy to defend spots (like base enternances) with no “depth” (turrets or acid tubes) behind them protecting the vital structures. In that case, skip destroying fortifications - dash past, and take down the eggs/telenodes, armory,reactor/overmind!

Camping
Camping (sitting in one spot and waiting for prey to come along) is a controversial strategy. In many common first-person shooters, camping is regarded as “noobish”.

From a tactical point of view, camping might actually make sense in some situations:
 * 1) as humans need to return to base (or outpost) for healing and refilling ammo, and human bases are usually well defended by turrets and teslas, it's not uncommon for humans to stay in base and just fend off alien attacks. Also, in the safety of their base, humans can use chaingun while kneeling down, without encountering the drawbacks of limited agility. However, in the end humans will have to go out and attack alien base if they want to win, so base camping makes only sense as an intermediate stage.
 * 2) aliens are not bound to their base as much as humans (because they heal automatically and don't need to refill ammo), so a viable tactic for aliens can be to camp at the entrances to human base and kill single (desperate) humans that try to get out. If the human team doesn't start a coordinated attack against the camping aliens, this tactic can help to wear down the humans credits and finally attack the human base.

Despite its potential tactical advantages, one should keep in mind that many players are plainly annoyed by camping, and also that extensive camping is actually forbidden on some servers.