Technologies can be researched in the bunker. Researching a technology will unlock new crafting recipes and/or unlock more technologies to research. Most technologies have a resource cost to pay in order to start the research, and take some amount of real time. The time passes even when outside the bunker or offline. Starting another research while one is in progress will pause the current one without losing any progress, and paused research can be resumed at any time. Unlike with crafting, you cannot queue technologies to research.
