I always found it frustrating to be limited to researching one topic at a time even if I have the research points to study a dozen low level techs. Especially as I might be concentrating on one or two things but still need all the other techs to have a decent empire.
What about dividing things into to two areas discoveries and tech levels.
Discovers would specific things like ion cannons, or fusion drives. A Tech level in a simple version would be a set of discoveries.
The research points you generate are spent on discoveries, and when your total research points generated reaches a certain milestone you get all discoveries at that tech level.
So tech level 1 might consist of
- Colonization Module
- Fusion Engine
- Vertical Farms
- Research Labs
- Industrial 3D Printers
- Digital Currency
- Solar Collectors
Each costs 10 RP. The cost of unlocking Tech Level 1 might be 150% of the remaining techs. So If I researched just Fusion Engines and colonization module from tech level 1 then when my total research reaches 90 RP I'd get all the remaining ones.
You can have other more complex interactions as well. Such as TL cost is decreased by 10% for every level behind the galactic average you are. Or you get a 2.5% discount for every race you have a trade agreement with. Covert action might be able to disrupt your progress towards a tech level. You might find the ruins of an ancient planet civilization that instantly catapults you to tech level 3.
That way you focus on a couple of primary techs an know that you'll still advance as empire as whole, even if all do you is spend your time researching bigger guns.