After a game where the whole world was outteched by an AI that expanded like mad, and after doing so myself a few times, I started thinking about a solution. And so I got: universities and laboratories reduce science in each city by 1%. It fits all criteria (imo):
- Gameplay: takes away some of the large science advantage of large (wide + reasonably tall) empires, while barely affecting (pure) tall empires.
- Realism: A university drains the brilliant minds from other cities to work there. When universities are widespread, the entry level lowers and less research will be cutting edge. Also, competition for publications will increase pressure on scientists, leading to rushed, poor research or even fraud.
- Control: cut down on universities to keep the negative effects low. Adopt Free Thought.
- Decisions: follows from above. Putting a university in every tall-ish city is no longer a no-brainer.
- AI use: it takes over 30 cities to really wander into negative effects, so this is at worst just another bad AI priority. But if the AI hits 20+ cities, just how bad can it be doing to begin with?
- Modding: totally easy to implement.