Well, to make winning more inherently fun, you can make levels in the game. After a player wins one level, the player goes on to the next level. This way, there is a sense of progress in the game. Making levels in this game is fitting to this game and can make winning more fun. As for the gameplay, maybe you can make the enemies shoot the player and you can make the player also have the ability to shoot enemies. Then, you could have the enemies and player have health (and the player should have more health than the enemies because he or she is alone). If the player dies, the player will have to restart the level. If an enemy dies, it will disappear. Every few seconds or so, another enemy will spawn. It would also be interesting if the NPCs also fought each other (since there are three types of characters in each game and two of the types are competing NPCs). While fighting, the player should also have the ability to put more paint on the canvas if they are concentrating on painting (e.g. pressing some buttons that are hard to press while fighting). By doing this, the player can get an immediate sense of danger that can compromise the player's objective, but the player would also have to think in the long term and actually try to get most of the paint on the canvas.