- research-upkeep: slowing research down if you have researched more
- research-upkeep-as-production-bonus: if you have researched less, an effect increases a bonus to planetary research production
- research-upkeep-as-production-malus: if you have researched more, an effect decreases planetary research production
- research-upkeep-as-tech-cost: if you have researched more, all techs cost more RP to research (there is currently no way to distinguish malus from bonus)
- research-upkeep-as-individual-tech-cost: if you have researched more, some techs cost more RP to research
- research-upkeep-as-cheaper-enemy-tech: other empires have to pay less for tech, the more one researches
The difference between malus and bonus is mostly a effect accounting UI issue, with some secondary complications. Where there is no effect accounting presentation (e.g. tech cost) one cant distinguish between malus and bonus.
For research-upkeep-as-production-bonus:
So you would start with maximum bonus to research production? That ratio could be a game rule. Maybe maximum 500% going down to minimal 100%.
For "its stupid to get tech for (almost) free" tech independent upkeep would need to be based on the number of techs, not on the research points spend.
If we could find a formula for the ratio I think that would be rather a stop gap solution. I am pretty sure we should throw it away when we switch to tiers and themes.
Another completely different idea: research-upkeep-as-special-tech-sale or research-upkeep-as-research-progress:
after finishing researching a tech, the user is offered some options for a special deal for researching certain techs cheaper. the level of cheap being determined by what the other empires already researched (for catch-up) and what your empire researched (the more your researched, the lower the discount). On offer would be directly researchable techs. Minimal "discount" would be 10%. In the KISS implementation if you choose one deal, you would get the progress of the discount (so 10% if tech costs 100RP, research progress would be at 10% and you would only have to spend 90RP). Probably the tech should also be queued automatically.
Fluff would be rather something like "focused research gain". Of course one could remove the optional part and have an effect distributing research progress. That could be almost scripted with the current implementation.
The main problem with all those bonus oriented approaches: fives times almost-for-free may be still almost-for-free. And having huge discounts for scaling - like ten times research production or 90%-off look quite weird i think. And for research-upkeep-as-special-tech-sale, everything outside off sale would be ridicously expensive.
I would prefer something similar to research-upkeep-as-individual-tech-cost, maybe research-up:
For me a tech dependent bonus/malus like a current tech level and researching tech at your tech level is significantly cheaper would make most sense to me (although having the bigger UI challenge).