I enjoy when DFS sites offer occasional promos besides DFS (like Squares contests recently with FantasyFactor, bingo with FanDuel). Something that seems different, fun, with a good chance of winning some $.

Anonymity would probably be a given for a crypto DFS site.

There are variety of things you could do to attract clients (like deposit matches, no-deposit bonuses, freerolls, etc), but what will ultimately decide if people want to STAY playing on the site will be their perceived ability to actually win (though there are always people who just like to gamble and throw a lineup out there kind of like a lotto ticket). Sharks generating tons of lineups have infested DFS sites in recent years so anything that limits that is helpful - single entry contests, "beginner only" contests, etc are a good start to help grow the player base.