Working at Hadean requires a certain kind of patience and a strategy for dealing with the work environment. What follows are insights based on my own experience, as well as that of my Hadean current and former coworkers. Your milegage may vary (see below), but the goal here is to both help you decide whether it's a right job for you, and to help you stay sane if you do join.
1. Do not join Hadean if vyou are in a bad negotiating position. The easier you are to replace or strong-arm, the worse your treatment is going to be. This varies much more than you'd think, while key programmers experience relative peace (relative is key word here), employees in positions that are easier to replace or no longer necessary can experience insults, yelling, bullying, be expected to be available 24/7 and get a meager pay. If you're not a software-related hire you should probably avoid Hadean entirely.
2. Do not be a hero. Hadean loves heroes, or as they put it "people who put Hadean first". There's a yearly vote for the best employee. The CEO loves to publicly praise exceptional performance. You'll potentially get a better perf review for being a hero. So, why not? IT'S A TRAP. First, the recipe for being a hero is simple: the more of your life you put towards the company over yourself ("Hadean first spirit") the more of a hero you are. What does the CEO praise people for? Coming to the office early and leaving late. Working unpaid overtime to secure a contract. Being always available. Having the largest number of git commits. Second, being a hero doesn't guarantee a better treatment. In fact it seems like it invites misery because you're being perceived as being more tolerant of bad conditions and long work hours. As a result heroes are more likely to be put on the critical projects (believe me, it's the last thing you want) or get "promoted" to a position of more responsibility without a payrise. The data is in, while heroes burn out and leave (2 former heroes have very recently left in fact), the "background" employees are still happily working.
3. Maintain healthy boundaries. Hadean's management will keep trying to squeeze out of you as much as possible step by step, while trying to spin this as "growth". Finding employees with "growth potential" is in fact an important goal of the recruitment process, as evidenced by questions aimed to determine how "malleable" (read: are you inexperienced/vulterable enough to be coerced) you are. It's not an accident that for a large percentage of the employees Hadean is their first job in the industry - it's way easier to convince an inexperienced person (or someone with impostor syndrome) that "this is normal" or "this is just how things are in a startup" or "this has to be done at this stage in the company lifecycle". Over time, the expectations can increase to unsustainable levels, but where they really peak is "critical projects" where you are not only expected to do lots of overtime, but you are also expected to cancel your holidays or in extreme cases even sick days. There's a straightforward solution to this: remember that you have worth as a human being and maintain your boundaries. To prepare for the absurd deadlines cap your day-to-day efficiency at 60-80%, so that you have some spare capacity to give when the "critical projects" come at you. Do not bring attention to yourself to avoid ending up in the critical projects in the first place.
4. We are stronger and better informed together. Sadly, you can't exactly trust the official information coming from Hadean's management. The lies and omissions vary case by case. Sometimes the company will tell you that someone resigned, when it fact they were fired during a pandemic, other times they won't tell you that your manager has left until he's actually gone. Sometimes it's trivial stuff like gaming the system by asking employees to post positive glassdoor reviews (see march 2018), other times it's your manager blatantly lying to the rest of the company about project's progress or abusive employee behaviour is being swept under the rug. The effects of these lies on trust are exacerbated by the fact that there's no way to discuss topics like these publicly without facing consequences. Therefore, having a network of people who you can talk to privately and cross-validate the official information is of utmost importance both for finding what's going on and for seeking support in case of facing unfair treatment or discrimination. Apes together strong!
Once you know what to expect and follow the above advice, Hadean isn't that bad, but it's definitely not a job for everyone. For me it makes up with the fact that the work itself is something I personally like to do. The experience can also vary over time, it can be decent for a while, then turn into a horror for a couple of months, then be better again.