Some notes:
* Lose 2x against the male fausts to collect both events (level1 loss + level2 loss events).
* Win vs both female fausts to collect both events.
* Some decision leads to different male fausts spawning. My current theory is that female-faust defeats affect the male fausts who spawn.
* "Skip Events" will cause you to miss out on CGs. Prefer to push the CTRL button instead if you want to fill out the CG Gallery. For some events (in particular: the male-faust lose events), you can recollect the CGs by entering "Replay Mode". But the Brutal scenes for D2 energy will need to be replayed if you "Skipped the rape scene".
* "True End" seems to require "Max love" or "Max Brutality" for their respective routes (level 5 love or brutality).
* Max corruption causes a loss + CG event.
* Minimum peace causes a loss + CG event.
* Brutal end and True Brutal ends are sad, downer endings.
* True Love end has two final bosses after the credits roll. Be sure to save up enough D2 power, max out your stats, and get good skills equipped if you hope to win. Losing vs the first final boss causes a CG event. I don't think the 2nd final boss has a CG event involved.
* Ikaro (Wolf) has two losses at two different points of the story. Losing the first time causes him to disappear forever (bored of Earth, so he leaves to conquer other planets IIRC). The 2nd loss is an instant game-over event.
I haven't gone through all the routes yet, but hopefully the above notes help people out.