Absolutely everything and anything should be acceptable. The idea that crossing the line twice isn't just accepted but encouraged was one of the many things that attracted me to EP. I saw Momo VonSatan and knew I was on the right track. I found the Carnival of the Goat and knew I was home. For instance my character at the moment has been a porn actor in the EP setting for 70 or so years. I enjoy coming up with the ridiculous scenarios that his productions have had and slapping a ridiculous title on them. Knowing Industrial metal does help me title them appropriately. Now sexual abuse also makes for an applicable backstory. The setting has rampant sex trafficking, which can include terrible sexual abuse. Add in mind editing and you may have a poor hollow shell of a person who doesn't even know the extent to which they are being abused. This is a mature horror setting, such things help create the mood. That being said there are a few places to draw the line. Foremost unless you're playing "ERMAGERD AN ERP!" where they asked for it, the ST should not actually force such situations on to the actual PC's. The PC's finding out someone they care about has been made an indentured adult entertainment specialist can add some drama to a sideplot. Doing that to a PC is usually beyond what is acceptable. The second is length of description. This is especially true for large groups that meet in real time. No one needs to have to sit down and listen to pages of descriptive, blasphemous, gore-porn being recited to them. The augmentations of the scum with the three foot long tongue extension and an extra set of eyes where their nipples should be, can be described in just that many words. Even in situations that include full nudity the players are unlikely to get more than a glimpse of someones intimate regions unless they are actively searching. Even in play by post the limit for such descriptions is really only expanded by another sentence. You may occasionally run into an ST and/or group that has no interest in "ERMAGERD ERPS!" but still wants to fully explore the deprivation of transhumanity. If everyone in your group is one of them don't worry about asking, you'll know. It's up to you what you do them. Much the same if one person in your group is interested in that and everyone else isn't. Edit: So what strange scenario's can you come up with?

In my EP games I started with murderous neotenics, voluntary slavery and brain hacking in the first adventure... my players did not bat an eyelid. Maybe they are a bit too used to my games. Good gaming stretches boundaries - about what you think about, what you create, how you play. That almost requires things that are on the edge. But doing it right requires a bit of cooperation and sensitivity among players and GM. One of my best campaigns ever has one PC break down and commit suicide. The player had decided that he was too uncomfortable with the campaign, and decided to go out with a bang. The character was already pretty unstable and a breakdown was not too implausible (another PC has betrayed him and revealed a past crime, and now the media and authorities were closing in on the formerly celebrated hero). Since much of the play happened on an online forum the increasingly erratic IC posts from the character were really hard to distinguish from evidence that the *player* was going mad... it was creepy as hell. Afterwards we all agreed not to go there again, but it was an amazing experience. I have no doubt other gaming groups would be uncomfortable with human/uplift sex, running genetic algorithms with modified forks of yourself, market based ethics or the PCs having to kill large numbers of innocents with WMDs in order to save transhumanity - the trick is to see how much such themes can actually be touched before things go beyond stretching limits and into grossing out/angering the players.

Talking to players ahead of time is good, however not everyone even knows their limits or wants to talk about them. It's usually enjoyable to push the limits a little bit, but if you spook a player it gets un-fun pretty quickly. So watch out for their reactions and scale it back at the first sign of trouble.