Metal Slug XX (reads Metal Slug Double X) is a enhanced modification of Metal Slug 7, released in December 2009 for the Playstation Portable and Xbox Live Arcade with new content. These are backwards compatible with the PlayStation Vita and Xbox One. A remastered version for the PlayStation 4 is set to release on Summer 2018.
- The screen is not re-dimensioned anymore, like in the Nintendo DS. Additionally, the player can select the aspect ratio of the screen:
- 4:3 (Classic aspect ratio with designed borders at left and right of the screen)
- Wide (Fullscreen)
- Clear (Like "4:3" but with a smaller screen for better visual quality)
- Rebel Troops reuse their sound effects from Metal Slug 6 (PSP only).
- Old enemies reappear again, such as the Mars People and the Hunters.
- Change in items, Slugs, and enemy placement.
- Multiplayer mode by using ad hoc and online services. Unlike other games, there is no drop-in multiplayer,
- Leona Heidern as a downloadable character (Costs $0.99).
- Altered missions in the Combat School mode. The Item Collection challenges are replaced by the returning Survival challenge and Super Devil rank.
- New Special Moves:
- New Hidden Routes:
- Mission 1 - There should be a pitfall/hole before the Di-Cokka and the DANGER barrel. Go there and fight the hunters.
- Mission 5a - When you reach the end of the second part of the stage, it says GO right. Instead, go left until you find a teleporter. Go in the teleporter and fight UFOs and tons of soldiers.
- Mission 5b - Just like Mission 5a but do not go in the teleporter. Jump over it. You should fight hordes of Mars Peoples in there.
- Metal Slug XX is the third installment in the series to increase the number of playable characters, from 6 to 7 with the addition of Leona.