The Future Rebels brought two, giant, mechanical monsters to the present. The vehicle the player rides on has a Vulcan in the front, two movable arms, and a shock wave attack that serve as bombs.
As the Slug Gigant takes damage, the cockpit visibly breaks until the player is left fully exposed. The player is unable to get out of the Slug Gigant, so the player dies once the vehicle's health reaches zero. The Slug Gigant remains sitting down headless until the player respawns flying inside of a new cockpit.
When in Co-op, both players use the same Slug Gigant. Player 1 controls movement, the forward Vulcan and the claw-blaster cannon, and Player 2 controls the original Vulcan from Metal Slug 7 planted on its shoulder. Each time the Slug Gigant is damaged, both players switch control of the Slug by means of swapping controllers (P1 becomes P2 and vice versa). As both share the same Slug, they both die when it's destroyed.
At the last part of the mission, Allen appears with his own "Gigant" with different weapons. The boss is fought with the Slug Gigant. The players does not earn any bonus points for the Slug because of this.
In other games
It appears as a free event unit after finding all of its hidden parts in different areas in the 1.32.0 update. The Slug Gigant costs 999 AP and is tied with the Stone Turtle as the toughest unit in the game.
The Slug Gigant returns as a Super Rare unit. It can be upgraded to shoot more shock waves. Three new variants are introduced.
- Slug Gigant: The original giant snowplow. It's found in Mission 6 of Metal Slug 7/XX. Clark rides this Slug in Metal Slug Defense and Metal Slug Attack.
- Slug Gigant MK II: Painted blue and ridden by Ralf, this Gigant fires four shock waves (two in the air and two on the ground) as its long range attack. It's special is using the Metal Slug XX Vulcan to rain shots onto the opposing army. Only found in Metal Slug Attack.
- Golden Slug Gigant: Painted with gold and ridden by Marco, this Gigant does not have a long-range attack; it only has a short-range attack that consists of smacking enemies with its golden mechanical arms. Its special attack is firing shock waves like the original variant. Only found in Metal Slug Attack.
- Slug Gigant MK III: Painted gray and ridden by Tarma, this Gigant fires one shock wave and swings its arms at the same time. Its long range attack is using the Metal Slug XX Vulcan to rain shots onto the opposing army. Its special attack is charging forward. Only found in Metal Slug Attack.
- Gigant is based on the word гигант, which means "giant" in Russian. Gigant is also a synonym for "giant" in German, the more usual word being "Riese". Gigant is also a Polish word that also means "giant".
- This is the only Slug vehicle which shows damage from being hit. This is unlike the Slugnoid where it only loses its Vulcans but doesn't show any visible vehicular damage.
- This Slug is the largest one and the one that can take the most hits ever in the series.
- The Slug Gigant MK II is the first Regular Army unit in Metal Slug Attack that serves as an event boss.
- Metal Slug XX PSP manual, pg. 18. https://www.yumpu.com/en/document/read/20457385/to-view-the-metal-slug-xx-manual-atlus