Rat Race

Rat Race is a multiplayer map in Halo: Combat Evolved.

Summary
It is a circular map, with a multitude of Teleporters, tunnels and passages.

The most notable feature of the map is the central section, which consists of elevated tunnels. There are two entrances to this complex, one by a teleporter and one by an inclined ramp. The strategic value lies in the two exit points which allow a player to drop unexpectedly from the ceiling through a wide hole into the enemy section of the base. Since this is strictly a one-way vector of attack and jumping down this hole usually entails grabbing an Active camouflage or Overshield power-up, defenders are forced to keep an eye on the ceiling.

Although the Bungie.net description claims that it is a UNSC attempt to mine into the surface of a section of Installation 04, the fact that the crew of the Pillar of Autumn would have had only 2 or 3 days to set it up makes this unlikely. Likewise, it is not known where they would have found the equipment necessary, or the time to do this. Why they would attempt to mine the surface of the ring is also unknown.

Capture the Flag

 * First, if located on the "base" (there are no buildings in Rat Race, only the flags) that has the flamethrower, get it. It is the best weapon in the entire map.
 * If you're at the enemy base, do not act miserly and only chuck one grenade. The other team will spawn there, and your grenades will weaken them to the extent that you can finish them off with any weapon.
 * If you have frags, use those up before employing the plasma counterparts. They are much more destructive unless you manage to "stick" an opponent.
 * Before charging to the enemy flag, keep an eye at the ceiling. There should be either an Overshield or an Active Camouflage, both of which are priceless assets.
 * Go through the tunnel towards the enemy base, and you should be provided with an ideal spot to jump down to retrieve the flag. Your opponents will not see you unless you jump down, or you show up on their motion tracker.
 * The two Covenant portable shields can be used for camping. Use this to your team's advantage by hiding there as your team's flag carrier escapes, and blasting pursuers.
 * This can be turned against you however, by using the "Noob Combo": an overcharged plasma pistol shot to disable their shields, then an assault rifle burst to kill the camper. This method only works in "No Shields" games; however, substituting the plasma rifle for the plasma pistol is a good way around this problem if shields are active.

King of the Hill (Team)

 * You can spam grenades to either hold off your enemies or confuse them.
 * If it is in an open area, the hill will become extended. Therefore, you should be wary of hiding locations that a crouching and silent opponent might be able to use and evade detection (giving the other team time).
 * At close range, an expert player wielding a shotgun is arguably the most dangerous one. If given the chance, always take it. If possible, get a plasma rifle to take down their shields.
 * To counter a player with a shotgun, you can either spam grenades, pistol snipe him (you might require a reasonably distant range and skill) or use the fire-melee tactic from the assault rifle.

Trivia

 * The structure of the level resembles a parking lot's up and down ramps.
 * Other than Longest, it is the only map in Halo: CE that lacks the sniper rifle (Though the sniper would not be useful on this map).
 * You can knock down either the Active Camouflage or Overshield by shooting them.