Online (unlocked at Level 10) is the only real-time PvP mode available in Metal Slug Attack and is equivalent to Metal Slug Defense's Wi-Fi VS. Before starting a match, you can change your deck if needed.
To win a match, players must destroy their opponent(s) base. There is a timer of 300 seconds; if neither side is able to destroy their opponent's bases by that time, one side will win while the other will lose regardless of progress.
If one is a member of a Guild, they can initiate a 1-on-1 or 2-on-2 sparring match [as of 1.5.0] against their guild mates (no rewards given, including Daily). Unlike Exercises (played against the AI using the guild mate's deck), these matches are real-time against the other player.
Players can set which message to display to an opponent before the match:
- Have fun!
- Serious match!
- I'm a newbie!
- Looking for friends!
- Will complete the mission.
- Come at me!
- Not done yet!
At the end of each battle, they can additionally opt whether to send a "Good Job!" message to their opponent. This has no bonuses and is simply a compliment. The battle is kept in the players record (currently unknown how much can be recorded at a time) in four separate pages.
The first page is very simple, containing the amount of damage dealt, the amount of kills obtained, the amount of AP that was used and their AP production level. The second page lists the top damage dealers in that battle. The remaining pages (2 in 1v1 or 4 in 2v2) lists the units in that player's deck with how much damage they dealt/took, how many kills they obtained, how much times that unit was deployed (along with AP costs) and how much AP that unit gained.
A popular Online mode as it pits you against a random opponent.
When playing 1-on-1, players can determine the opponents they want to fight in three categories. The game advises you that with less filtering options put in place, you will find a match faster:
- Everyone - You battle anyone regardless of their level.
- Within 5 levels - You battle anyone that is at your level, or five levels above/below you.
- Your level - You battle other players that are at your level.
Once you create your filters, the game will connect you to another opponent. Once the game finds an opponent for you, you will be shown the opponent's level, their amount of wins in 1-on-1 mode, and the units in their deck (including levels and unlocked skills).
After the battle is finished, you or your opponent may opt for another match if desired. If you or your opponent agrees to the rematch, the battle starts over again.
The less popular of the two modes, 2-on-2 modes allows four players in two teams to battle each other. It is less popular then 1-on-1 mode, since there is typically a longer wait time. In addition, curb stomping battles are more likely to occur, as this mode forces random people to a team regardless of their levels. As a result, players are unable to determine how strong their ally/enemies are until they deploy their units.
At the end of a battle, players must exit the result screen and select the 2-on-2 option again if they want to continue battling other players.
2-on-2 mode features extra commands for basic communication. 2-on-2 mode wins/losses are separate from 1-on-1 matches.
- For every 5 victories (in any mode) the player is rewarded 10 that can be collected in the Mailbox.
- For every 1,000 points (in any mode) the player is rewarded 5 that can be collected in the Mailbox.
- 30 from Daily.
- Bragging rights for making top 50 in the Online Rankings.
- Player Insignia (derived from United States Army) representing Online Rank (visible next to the user name) changes as the total score goes up (see the table below). It is strictly cosmetic and offers no practical benefit.
- The amount of points earned varies depending on the difference in units killed by each player. In 2-on-2, that includes difference in kills between allies.
|3,000||Private 1st Class|
|20,000||Sergeant 1st Class|
|50,000||Chief Warrant Officer|
|2,000,000||General of the Army|
- Actions are executed with a delay (with a length depending on the quality of the internet connection on either side), so a player needs to learn how to time their actions to achieve the same results as they would have in delay-free singleplayer.
- Occasional cheating is encountered, including:
- Instant recharge of Metal Slug Attack, Recovery, or Repair powers.
- Instant unit production with no AP cost.
- A rare bug can occur where one of the player's bases may end up being indestructible.
- If a player disconnects the match by turning off their data connection, once they've seen 'Mission Start' after finding another player to match. They may able to destroy the enemy's base with ease, giving them additional points.
- One of the maps (the rebel base next to the forest in Metal Slug 3) is partially glitched with a slight elevation increase. This only affects players using Beatriz if they start off from the western base zone.
|Metal Slug Attack|
|Game Modes||Another Story | Attack! • List of Standard Missions • List of Elite Missions | Battle and Team Battle | Combat School | Extra Ops • List of Extra Ops Stages | Online | P.O.W. Rescue | Special Ops|
|Features||Level and EXP • VIP | Build Up • Units • by Icon • Teams • Stats • Items | Guild • List of Guild Raid Stages | Daily Login • Daily Quests • Events | Power-Ups | Mystery Crank • Treasure Hunt | Shops|