If you've played the game "Bookworm", it's a cross between that and slither.io. The theme is "Joined Together", so I joined together two games that I liked.
The top half of the screen is slither, definitely (I even noted it in the About section in the game itself), but to actually get proper points, you build words with the letters you gained. (Hence the "Bookworm" part.)
So with the two games joined together, the game is pretty much an exercise in how well the player can multitask, which means it's more than a sum of its parts. Do you want to get points by making words and take your attention away from the snakes on the board, or do you focus on avoiding other snakes? Something like that.
It's enough of a twist to build upon the concept, I think.