Its funny when people use the term 'ORM' when there is no ORM in sight (I know I do it to :). BTW there is no 'Relational' and no 'Mapping' in the C# Redis client, For max speed POCO objects are just serialized as JSON or have their primitive values stored in Redis's Sets/SortedSets.
I said ORM because the github project description says "...built with ServiceStack, C# RedisClient, OrmLite...". Just realized now that the SO clone is just one of several sub-projects within that repository, sorry.