Near deserted planets

[Coalition]

Wouldn't be allowed? Says who? Who enforces these rules?

It sounds like an agreement among the different empires, where they wanted to avoid 'Arena' situations, without going to war with each other.

Must be fun imagining all the discussions that led up to that sort of agreement. The timeframe that was agreeable to all, the definition of what 'presence' means (along with defining 'too much presence'), and the effective radius ceded to the owner. I wonder if the 'presence' was specified as using only imported materials (so no mining operations before the year is up), limits to scientific learning (send a copy of everything you learn to the other parties), plus a certain limit to the amount of materials stored on-site (i.e. 1 year of MREs so no need to import food). By having a symbolic need for transportation, this would allow for a 'blockade', allowing the other side to cut off access to the planet (and still be able to feed the crew on the surface out of its own stores) in order to force a reset of the 1 year counter. Some empires might even have scout ships with several setups that allow them to establish a presence in multiple systems, logging them for their empire.

The other counter would be remote probes that empires might send out to candidate stars, to monitor them in case the other side establishes a presence. These would be cheaper than an outpost, but as a remote probe does not qualify as 'presence', they do not serve to claim the system. The probes would transmit data back if they detect anything 'notable', and the group receiving the data would decide what to do. Not receiving a signal would also be an alert, to find out what happened.

[Graham Kennedy]

Wouldn't be allowed? Says who? Who enforces these rules?

The galactic-level powers, which is any nation that is capable of, and interested enough to, project military and diplomatic power across galactic distances.

Rather like the present day, how much the rules and traditions of galactic behaviour are enforced depends on how determined the other nations are in enforcing them - and that depends on how much they care. Some try to enforce codes of behaviour rigidly because they believe in them, some because they don't want the home media saying "Wow, look at what's happening, and we stand by and do nothing!" Some even use them as an excuse to engage in vendettas.

So if a really high level galactic power broke the rules, then probably nothing would happen. Just like basically nothing happens if the US breaks international law, because at the end of the day, what can anybody really do?

The Coalition is at the lower end of the galactic power scale, and regarded by most as a bunch of upstart newcomers. Whilst they do have allies, there's also a fair bit of resentment directed at them. As such they try to be an exemplary galactic citizen, to try and accumulate some credibility and to try and avoid giving people who don't like them an excuse.

In other words, there are theoretical rules of behaviour, but to be honest it's more realpolitik than anything.

[Black Jesus]

Made me think of an 80s New Zealand movie called The Quiet Earth. It's about a man who's seemingly alone on the planet for a long time after a disease has wiped out mankind. Not an identical scenario, because he lives in and off the remnants of society, but the psychological effects must be rather similar.

Sounds a lot like George R. Stewart's 1949 novel "Earth Abides." Excellent read.