Attack!

**Attack!** is the primary singleplayer mode of Metal Slug Attack and represents a direct improvement of the **Sortie** game mode present in Metal Slug Defense. This mode is the main source of **EXP** (the others being Daily quests and Extra Ops events),  MSP,  Items (all tiers except Platinum), and  Unit Parts. It is also the only permanent game mode to consume  **Sortie Points** to play, rivalled only by Extra Ops events.

It is in every player's best interest to advance through World Maps. Every regular (Standard or Elite) mission completed for the first time gives the player  30, and boss missions at the end of every region give  60. On top of that, every day at 0400 hours server time players are rewarded MSP via the **Mailbox** for the total number of stages cleared and not currently under attack (**World Clear Reward**) -  70,000 at most.

There is a chance to unlock Special Ops, Extra Shop, Rare Shop, or Rare Boss upon every victory (auto-resolve raids do not count).

## Sortie Points

**Sortie Points** is an automatically renewable resource used in this game mode (and Extra Ops events) to start any and all missions (except the Day Specific Mission). All SP spent are converted into EXP and Guild Points at a ratio of 1:1 regardless of the outcome.

SP regenerate to a certain point that can be extended as the player grows in Level (+1) and buys Sortie Level Upgrades (+2). Capacity can be exceeded with special SP rewards, but SP do not regenerate until brought down below the limit.

SP has a "soft" cap of 9999; after which any more sortie points after that will not show, but any obtained once this cap is reached is still added to the player's total sorties available.

There are several ways of obtaining SP:

* **Waiting** -  1 every 3 minutes.
* Completing **Daily quests**:
	+ 60 immediately and for completing 5 and 10 daily quests.
	+ 100 for completing 15 daily quests.
* **Levelling up** adds  50 plus the amount equal to the past level.
* Giving a guild mate a **Good Job** bonus:
	+ 15 (they get  1,000) for free.
	+ 30 (they get  30,000) for  30,000.
	+ 100 (they get  50,000) for  30.
* **Searching** for  Unit Parts in Treasure Hunt (varies).
* **Purchasing**  120 with  Medals (prices are reset every day at 0400 server time):
	+ 30 with the 1st purchase.
	+ 50 with the 2nd purchase.
	+ 100 with the 3rd purchase.
	+ 200 with all following purchases.

## Standard Missions

*For a detailed stage breakdown and free units, see List of Standard Missions.*

Standard missions are fairly easy to beat and offer minimal rewards in terms of MSP and items, but cost less Sortie Points to run, which can be helpful if one needs to empty their Sortie Point pool before going offline.

Depending on how quickly one beats any given level, they are rated **S** (best), **A**, **B**, **C**, or **D** (worst), and are given an MSP Bonus (except D) as an extra fraction of the level completion reward. Scoring **S** allows the player to **Raid** the mission in question - automatically win it without neither a fight nor a grade bonus (equivalent to having the **D** grade).

The player can save concealed **P.O.W.s** in the course of playing through a level. In order to do so, one needs to deal a certain amount of damage over a hidden P.O.W. Their locations are scattered throughout the level, so activating special attacks early (before any enemies are in range) can be beneficial. Every saved P.O.W. drops a random  Item from the pre-determined loot pool. Automated raids result in a random number of P.O.W.s rescued.

Every boss level completed for the first time grants the player a pre-determined unit for free, which is equivalent of  10 - all units in the list being of Normal rarity.

Every once in awhile [exact times need to be verified] one of already completed missions is considered **Under Attack** (flashes red) by a random player or NPC deck of the same level, cannot be raided and needs to be taken over again. In this case the player can face much tougher enemies as they would normally do, but receive better loot (than that of the uncontested area - loot tiers scale up with player level, meaning that it is impossible to receive Bronze or Silver after reaching Gold) in full after a successful counter-attack without having to rescue P.O.W.s (pre-battle display does not necessarily match with the amount of items given post-battle). A maximum of 3 stages can be under attack at a time.

 41 | Gold x3
(except for Chicken)

 **Daily** quests offer **EXP** 120 and  10,000 [as of 1.3.0] for completing 1 Standard mission.

## Elite Missions

*For a detailed stage breakdown, see List of Elite Missions.*

Elite missions are more expensive to run and contain Standard enemy equivalents of higher levels, but offer bigger benefits:

* MSP per  SP ratio is higher.
* Higher tier items are available sooner.
* Unit Parts can be obtained.

Unable to be contested, each Elite mission can be attempted 3 times a day (refreshes at 0400 server time), although one can buy more attempts with  Medals.

 **Daily** quests offer **EXP** 150 and  20,000 [as of 1.3.0] for completing one Elite mission.

## Day Specific Mission

Every day at **0400 hours** (server time) a special boss stage appears and stays open for 24 hours. Players don't spend Sortie Points on fighting the boss but can defeat it only 2 times regardless of difficulty, and no EXP is rewarded. Harder difficulties are unlocked as one's Level reaches certain points and grant bigger MSP and Item rewards:

 **(Base)** [as of 1.4.0] | 6,000

**Note:** Hell difficulty is called "Ultra Hard" under the difficulty selection.

 **Daily** quests offer **EXP** 50 and  5,000 [as of 1.3.0] for defeating a boss once.

Each day bosses featured in the Day Specific Mission change as item rewards do:

**Note:**

* **Crablops** changes to the second form when its HP is below 30%.
* **Union 01**, **02** and **03** have respectively 50%, 20% and 30% of the total HP.
* **Green** and **Red Emain Macha** have respectively 60% and 40% of the total HP.
* **Amadeus Type: α** and **Amadeus Type: β** have both 50% of the total HP.

## Rare Boss

Within either 1 non-raid victory scored in Standard (including the Day Specific Mission) or Elite worlds, there's a chance (resets in 8 hours after triggering its appearance - best done at the time of Daily quest reset (0400 server time) and 8 hours later) to unlock a special boss stage featuring the **Rebel Gigant** that costs Sortie Points to play and offers bigger MSP rewards (than Standard and Elite) as well as Battle Medals instead of Item loot. This stage goes away after an hour and can be replayed as many times as one's Sortie Point pool allows (it is recommended to reserve SP bonuses, e.g. from Daily Quests), however with every victory Rebel Gigant's level goes up by one up to 50, and every five victories rewards increase as well as the cost of admission: