Reincarnation

Research
Research is unlocked after the first reincarnation, there are a total of 200 researches(as of V2.1.0), and many of them will not be unlocked until completing challenges and achievements later. Researches are bought with obtainium, one of the resources gotten from reincarnating, the green and red bordered researches are permanent, while the white ones reset upon ascension. See Research Guide for advice on where to spend obtainium.

Particle Upgrades
Particles are also gained from ascension, albeit at a much, much higher rate than obtainium, for instance you might get 1e400M particles and only get 1e60 obtainium(this is the only example I have, if someone earlier in the game could give a better example that would be much appreciated). Particle upgrades are the next, and currently last(as of V2.1.0) tier of upgrades in the upgrades tab.

Particle Buildings
Particle Buildings are unlocked with the first reincarnation, and are the 4th tier of buildings.

Anthill
Link: Anthill

Talismans
Link: Talismans