The major civilisations detected in Andromeda to date
Also known as M31 and NGC 224, this giant spiral galaxy is the closest major galaxy to the Milky Way. Both belong to the Local Group. Several relativistic craft, including linelayers with wormholes, have left towards the galaxy through history, although the chances that they will reach it intact are probably remote.
Andromeda has a number of characteristics that make it different from Milky Way; in particular it includes numerous large open clusters that have a wide range of ages, many of which are larger and older than those in the Milky Way. Conversely there are several young globular clusters in its halo, unlike those found nearer Sol. Some observers have suggested that these unusual clusters are the result of stellar engineering in the distant past.
Several xenosophont civilisations have been detected in the Andromeda Galaxy. These include HEEC-A-1, also known as Fullness of Life, an advanced utopian civilisation; HEEC-A-2, a migratory civilisation; HEEC-A-3, a civilisation occupying various types of garden worlds; and HEEC-A-4, also known as the Hyperblight, currently engaged in transapient-level conflict.
Other civilisations include the Golden Tower Builders, a relatively low-tech but widespread civilisation that builds innumerable megascale structures resembling arcologies, and a monocultural civilisation known as HEEC-A-5. More details here.