The fighter manages this despite suffering a 64% drop in sales from its launch week, according to Chart Track.
No new releases this week sees the top three stay the same, as Grand Theft Auto V holds second and Battlefield: Hardline is in third.
The PlayStation Edition of Minecraft enjoys a huge boost this week, with sales up 172% on last week, and helps raise it up five places into fourth, pushing down FIFA 15 to fifth.
The Xbox Edition also enjoys a rise up the charts, up two places to sixth as Call of Duty: Advanced Warfare keeps a grip on seventh.
Dying Light climbs two spots to eighth as a few games re-enter the Top 10 this week, both of which climb two places this week. You have Borderlands: The Handsome Collection, which finds itself in ninth whilst a price promotion helps raise WWE 2K15 to 10th this week.
Elsewhere in the charts, the only game to re-enter the charts is Tropico 5, which enjoys a sales boost thanks to its release on the PS4, following its PC and Xbox 360 release previously. It sits in 18th in the All Formats Chart this week and in seventh in the PS4 charts.
The UK All Formats Chart Top 10 (Week ending 25th April 2015) is as follows:
1. (-) Mortal Kombat X
2. (-) Grand Theft Auto V
3. (-) Battlefield: Hardline
4. (9) Minecraft: PlayStation Edition
5. (4) FIFA 15
6. (8) Minecraft: Xbox Edition
7. (-) Call of Duty: Advanced Warfare
8. (10) Dying Light
9. (11) Borderlands: The Handsome Collection
10. (12) WWE 2K15
You can view the full Top 40 here.
Another quiet week coming up, with the next wave of releases entering the charts in two weeks’ time.