Space mahjong

Space mahjong is a modified set of rules to mahjong. Here, the limitations on terminal tiles and honor tile are removed. Normally, the 1-9 scale ends with 1 and 9 as terminals. In this set of rules, the number sequence is given the wrap around effect when it comes to the formation of tile groupings.

Tile groupings

Due to the wrap around effect, the terminal tiles operate just like any other numbered tile.

Yakus

Chanta / Junchan

Aside from honor-tile shuntsus, there're two more available combinations of numbered-tile shuntsus: 891 and 912. This makes chanta and junchan become much easier than in regular rules.

Agari:

Kokushi Musou

Opened kokushi is no longer unavailable since honor tiles can be grouped as shuntsus.

Agari:

Though the value of such opened hand is usually reduced for balancing purpose, since it makes kokushi musou significantly easier than menzen one.

Junsei Chuuren Poutou

Theoretically a 9-sided wait hand is no longer limited to the regular one since numbered tiles can be wrapped around. That means such hand

Agari: (in regular rules)

can be interpreted as:

Agari: (in space mahjong rules)

Though depending on rules this may be recognized as a valid chuuren, or maybe not.