Survivium (2010)

You are a mad scientist designing viruses in a laboratory. You create a sequence of instructions such as move, rotate/turn, divide, eat, clone, jump, dash, or acid. Once the sequence is built, the virus executes it automatically in the arena. The goal is territorial domination: your virus had to cover more of the field than the enemy virus by destroying or outgrowing it. The core gameplay loop is: you program the virus, watch it behave, then go back to tweak the sequence if it failed. There are three main modes: training missions, duels between your own viruses, and online duels. The training campaign has missions of increasing difficulty, where you can unlock more actions as you beat enemy viruses.