Board Game Arena

Sevens, also known as Fan Tan or Domino and in Britain sometimes as Parliament is a straightforward game in which the object is to get rid of all one's cards by playing them to a layout.
BGA implementation also supports Shichi Narabe, which is a Japanese card game closely related to Sevens.

Please try the game here: https://boardgamearena.com/gamepanel?game=sevens

Bring back the second deck. One is kind of boring.

No.
Double deck variant is not popular as you think actually and it takes way too long.
Also, there are other variants for strategic games (eg. Killing Shichi Narabe).
Though there is no plan for increasing the complexity yet, if I have to I'd rather implement them.

Deployed a new version:
- Added 2 player mode (although it is not recommended to play 2-player games).
- Added Ristiseiska and related variants (Unlimited pass with penalty, Extra turn, Low first, Card value scoring).
- When the game ends by someone going out, the game log will display hands of remaining players.

How many passes are allowed per person? The rules here do not say, and in the version I know offline, passes are unlimited.

Supports 3 options: Unlimited, limited (max. 3), unlimited with penalty (last player to pass gets penalty unless they win)
Read table options for more information.

Thanks.