Armor Critical is a top down multiplayer PvP shooter. Originally called A.R.C. (Attack Retrieve Capture) and then Spark, Armor Critical is and has always been 100% free.
Players battle one another on player/community created maps. Use the arrow keys to move, tab to drop the flag, left click to shoot primary weapons, and right click to fire the selected secondary weapon.
One interesting game-play facet is that the only way to regain health (on most maps) is to kill other players.
Capture the Flag - Bring all the flags in the map to your team's flag holders.
Flip the Switch - Flip all of the switches in the map to your teams color (done by hovering over the switch).
Assassin - Each team has a flag carrier who is the President (only the president can charge and use grenades). Kill all opposing Presidents.
Turret Assassin - Turrets are non-moving targets that shoot back. In turret assassin, one team must destroy all opposing/hostile turrets.
Domination - Flip switches to gain points over time, until the score limit is reached (determined by map settings). Teams gain 1 point per switch per second.
Deathmatch - Kill or be killed. There is no win condition here. On maps with friendly fire enabled, this mode is every pilot for himself or herself.
Armor Critical allows players to customize their game experience extensively. Graphics and audio can be completely changed, causing quite a few players to create custom "patches" for themselves and the community.
All maps that are played are community/player created, allowing for an infinite number of play experiences.
1 hit: Used to tell teammates that a player will die if they take any damage.
h2s: Hit to smoke. A player's ship will being smoking when they are at or under 1/3 of total HP.
b: Base. If someone on your team calls base, your base is in jeopardy (they need help).
vulch/vulcher: Basically a kill steal/stealer (ks/kser). Someone who waits for their team to do all of the damage while they try to snipe kills is a vulcher (not vulture).
smoker: A player whose ship is smoking.
full smoked: A player has the maximum HP possible to still be smoking.
Shrap: Shrapnel. Grenades are all shrapnel damage, missiles will give off shrapnel if they hit a wall.
Spike: A sudden rise in latency which causes the player to "hop" on others' screens.
Spread: Laser firing technique.