Hackenbush is a game in combinatorial game theory played on a finite graph with colored
edges and designated ground vertices.
Player Left can delete any bLue edge, player Right can delete any Red edge, and either
player can delete Green edges. After a deletion, every connected
component disconnected from the ground is also removed. Under normal play, a
player who has no legal move loses (Lo 2013, p. 1).
A finite red-blue hackenbush figure has a surreal number as its game value. Allowing Green edges gives more
general Conway game values, which need not be numbers.
A few values are indicated above.