A cluster is a loosely-connected group of locations that make appearances in Submachine Universe.
Clusters are characterized by the presence of one-way karma portals between locations. When using a karma portal, the user cannot immediately return to the previous location until he/she has cycled through all linked locations.
So far there has only been one cluster found in the Subnet, the Jatsko Cluster, named after forum user Jatsko.
Locations connected in a cluster are accompanied by single-ended arrows ( → ) in their respective infoboxes. The addition of clusters necessitated a switch and delineation between single arrows and double arrows ( ↔ ), as there now is a distinction between one-way and two-way karma portals.