Suggestion: for new players (below xxxx rating AND/or below yy games (ladder+custom or just custom))
Allow them to get rating by beating some simple missions like games against sorian AI or maybe completing some survival map. New players can get like insta 500 rating for those, not so new players can get lesser rating boosts. Probably only allow to get rating boost only once.
Basic Missions ofc have to be designed/created.
I think it is ok to put minimum effort into that, just let them 1v1 a sorian ai on normal map with normal settings.
Maybe someone could make that happen