TL;DR
Buttons on the research screen that let us either hide all techs that use a given science pack or hide all techs that don't use that science pack.What?
- Selector on the research screen which shows all the science packs
- Each science pack can either be filtered for (show only techs which use that pack) or against (show only techs which use do not that pack)
- Multiple packs can be filtered at once; techs will only be show which match all the selected pack requirements.
- There's also a button for trigger techs, to either show them exclusively or hide them entirely. Obviously, this one cannot be combined with any of the pack filters.
- In the left panel where the techs are listed, filtered-out techs are hidden entirely, just like if you're using the text search bar and they don't match the given search criteria
- In the right plane showing the tech tree, filtered techs are still visible, but are greyed out.
- If the player uses the tech tree to select a tech which does not match the selected criteria, its entry is temporarily shown in the list on the left, but is also greyed out there so it can't be mistaken for a true result. Once they select a different tech, the non-matching tech vanishes again.