Mahjong Fix

[Naizakane]

4. Dora Kan
It should be impossible to get kan in dora. Any dora and ura dora tile is normally taken from the pile of all tiles. For example, if a red dragon is in dora, there should be only 3 red dragons left in game. Normally that's how it works because it is physically impossible to just get an additional tile to represent dora without picking it from the table. Same with Ura Dora.

This sounds like a problem you can only have with the dora indicator set to Doman. The difference between Traditional/Doman dora indicator is that Traditional dora indicators mean "the next tile in the sequence after the indicator is the dora" (for example, red dragon would be the actual dora because the indicator is green dragon, making a dora kan possible,) while the Doman dora indicator moves that one step ahead in the sequence for you. This is why dora kans are possible. For a more detailed example:

1. Dora indicator is flipped, revealing 3-sou (bamboo.)
2. Using the Traditional indicator, you count 1 step ahead in the sequence, arriving at 4-sou.
3. 4-sou is the actual dora. A kan of 3-sou is not possible, as one of the tiles is out of the game, but a kan of 4-sou is possible (unless it's also in the dead wall, either as a kandora or uradora.)

5. Last tile claim for tenpai.
Sometimes there is a situation when the player could claim the last thrown tile as chi or pon to earn tenpai in the end. Not win, but just tenpai. The game automatically ends because no one called ron on that last tile. But still, some players should be able to call chi or pon and get tenpai points.

And you would want to set yourself up for a potential houtei because...?