Sparrow mahjong
Description
Sparrow Mahjong (すずめ雀) is a simplified version of Japanese Mahjong (Riichi Mahjong). It was developed for those unfamiliar with Mahjong, and requires similar strategic thinking to standard Japanese Mahjong.
Rules of Sparrow Mahjong
The original rules of Sparrow Mahjong (すずめ雀) are summarized as follows:
- For 2-6 players
- 11 types of tiles (44 tiles):
- 1-9 of bamboo, 1-9 of characters (x 4)
- red dragon (x 4)
- green dragon (x 4)
- Basically 5 tiles in hand, 6 tiles after drawing
- 2 sets of sequences or triplets to complete hand
- No chi (chow), pon (pong/pung), kan (kong), or riichi
- Dora is the same as the revealed tile
- Red doras:
- all red doragons are red dora (4 tiles)
- all green doragons are NOT dora
- one red dora for each banboo tile type (9 tiles)
- Furiten: you cannot ron with a tile you have discarded, but you can ron with other tiles
Specifications in Pgx
Pgx implementation is simplified as follows:
- Only for 3 players
- Actions are only for discarding tiles (11 discrete actions)
- If players can win, they automatically win
- Players always keep red doras in their hands (i.e., red doras are not discarded if they have same but non-dora tiles)
- No Heavenly hand (Tenhou/天和) to avoid the game ends without any action from players
Specs
| Name | Value |
|---|---|
| Version | v1 |
| Number of players | 3 |
| Number of actions | 11 |
| Observation shape | (11, 15) |
| Observation type | bool |
| Rewards | [-1, 1] |
Observation
There are 15 planes in the observation and each plane consists of 11 tiles.
| Planes | Description |
|---|---|
| 4 | P1 hand |
| 1 | Red dora in P1 hand |
| 1 | Dora |
| 1 | All discarded tiles by P1 |
| 1 | All discarded tiles by P2 |
| 1 | All discarded tiles by P3 |
| 3 | Discarded tiles in the last 3 steps by P2 |
| 3 | Discarded tiles in the last 3 steps by P3 |
Action
Tile to discard.
Rewards
Game payoff normalized to [-1, 1]
Termination
Terminates when either player wins or the wall becomes empty.