A few days ago I posted about writing a game focus. I can give a couple examples by posting the focuses of my first two mobile games: Fish Feaster and TriGrid.
TriGrid mixes maze traversal, pattern recognition, survival, and hunting. You navigate a maze in order to eliminate all enemies. Enemies can only be defeated by running into them from behind but they can hurt the player by making any other kind of contact. There are many types of enemies and each has a special behavior. The player must observe the different movement patterns of enemies and maneuver in a way that catches the enemy from behind.
The art style and theme of the game is based on geometry, neon colors, and cyber-style text & music. The "characters" are colorful triangles, with the player's triangle having a different design than the others in order to stand apart.
Fish Feaster is a fish-eat-fish game where players choose a colorful fish to play as. The player eats several fish in order to grow in size while avoiding bigger fish that are trying to eat anything smaller than themselves. Players are rewarded for eating small fish quickly and avoiding hazards that prevent growth .
Fish Feaster is made with themes of variety and difficulty in mind. There are multiple colorful and vibrant levels that look very different from each other. The different levels have unique fish species swimming in them. The game can be unforgiving in that anything that can eat you will do so swiftly so great caution is needed to survive for long. Playing smart and finally beating a particularly chaotic level merits a strong satisfaction from players seeking a longer lasting game.