- Add more eye candy (juice)
- Find a theme that resonates but doesn't get in the way. Household chores (wall painting? retiling the tub?) might be a good theme, for example. Use the theme to explain the game better and give a more friendly FTUE
- Add some simple, skippable monetization (e.g. optionally watch a video ad to get your 2 daily retrys)
- Advertise the game on a lot of channels (facebook, google ads, whatever). Use small ad buys and keep track of where it works and where it doesn't.
- Don't add any sharing features (yet). As you grow your users, watch how they share organically. Do they post screenshots of the finished level? Do they ask for tips? When you notice patterns, build in game features to automate these behaviors.
- Port to mobile, and use mobile ad networks to further grow the game.
- Profit?? maybe? get cloned by somebody in three days? Get bogged down in rewriting for a different engine? Who knows? game dev is fun like that.
Unless lightning strikes, you're not really going to see much impact from sharing features and viral stuff until you hit a critical mass of players (like around 10k DAU maybe?) so focus on making the experience better for the core players at first. A whole lot of the "viral" stuff you see these days are seeded with paid promotion and ad spend at first.