Haphazard hobbyist programming sessions since about 1992.
(Hit Colors are used in conjunction with skins that use Custom Colors.)
3SPN Team ArenaMaster (TAM) relies on network replication to set the overlay color used to indicate that a player was hit.
In the Re mod, this logic has been moved client-side, thus freeing up network traffic, giving players quicker, more reliable feedback.
The RePawn class monitors changes to the (already) natively replicated OverlayMaterial, and updates the client-side pawn overlay colors accordingly, through the Tick function.