I believe the pills were initially cyanide (like in WW1 & 2), but then transitioned to some cocktail that included potassium chloride - rather than a fairly painful and messy poisoning. The latter induced some sort coma/sleep followed with a binary cardiac event. I cannot recall where I read that... so could be totally off base.
As to the military project versus colony statement - politically there has always been shared intent between military and scientific application of any space program - and before anyone jumps in here and cries BS, I am speaking from some experience. I think this needs to be carefully addressed in the setup story - is this purely a scientific mission? or is there a cross over bit of intrigue that may create factions in utilizing the resources and assets? If this was an MMO with a fictional backstory - the factions and international spying element could be quite interesting. All that set aside - most "realistic" science fiction sets the scenario with a military-styled organizational structure (even Star Trek). How that overlays long term socially with a more purely scientific mission could a great experiment and interesting debate. We see such success with the International Space Station, but there is still a pecking order - agreed upon through International Treaty and cooperative input.
If this is purely a private venture - then I believe socially this falls back into a military-istic format, but with ever increasing demands on efficiency and commercially viable exploitation. Also - historically and another common SciFi element is that criminals and/or the underclass are often drafted into such projects to be mechanics or just available muscle. There is not currently a role for this type in the game - the assumption being highly skilled and motivated scientists.
To bring all this back onto topic with the OP - whether a purely military structure or a more informal model - I agree that some kind of policy and plan will be played out to address not just a single isolated event (someone going bonkers) or a more insidious initiative (someone intentionally causing failure because of a philosophical difference with the mission or pure terrorism). Regardless - there will be a playbook that some ONE as the leader should follow (or NOT). And failing all - you can assume that some outside entity will come in and take control if the leader catastrophically fails the mission. I am wondering now if there shouldn't be a module that can be converted into a holding cell, with reasonable life-support facility.
- Disable and isolate an individual under (X) conditions through (Y) procedures
- Civil and legal obligations and definition of individual rights off-planet (Earth)
- Hearings/Reviews/Court Martial procedings
- Assignment of punishment, relative to problems
... and so forth. Maybe overkill for a game -
practically - the game host boots and bans the offending participant. But just MIGHT add some interesting back story to the game.