2187

1. 
   Break 2048

   Merge a 2048 tile
   13%
2. 
   Break 2187

   Merge a 2187 tile
   13%
3. 
   Into the Cube

   Start a 3D game
   56%
4. 
   Tesseract

   Start a 4D game
   44%
5. 
   Hyperspace

   Start a 5D+ game
   13%
6. 
   2048 in 4D

   Reach 2048 in a 4D game
   0.0%
7. 
   2048 in 5D

   Reach 2048 in a 5D game
   0.0%
8. 
   2048 in 6D

   Reach 2048 in a 6D game
   0.0%
9. 
   2187 in 4D

   Reach 2187 in a 4D game
   0.0%
10. 
    2187 in 5D

    Reach 2187 in a 5D game
    0.0%
11. 
    2187 in 6D

    Reach 2187 in a 6D game
    0.0%
12. 
    2D Limit · 2048

    Hit 65536 in a 2D 2048-mode game
    0.0%
13. 
    2D Limit · 2187

    Hit 59049 in a 2D 2187-mode game
    0.0%
14. 
    3D Limit · 2048

    Hit 65536 in a 3D 2048-mode game
    0.0%
15. 
    3D Limit · 2187

    Hit 59049 in a 3D 2187-mode game
    0.0%

Names, descriptions and icons are the game’s own, as Steam publishes them; the share is how many owners have unlocked each, from Steam's global figures for 15 of them.