So here is the current version of my upload/resurrection fantasy, as if anyone cares.
A benevolent alien or posthuman uses a time-viewer to scan your brain every night of your life. All of these versions of you wake up in idealized bodies on a simulated mini-world at solstice, each at the latitude where the day-length matches that of your original place and time. (I choose this arrangement mainly to mingle different ages.) This world’s axial tilt is that which makes the spacing most linear.
If you lived 100 years and your bodies are on average two meters apart on the sunrise line, the line is 73 km long; an adult can walk it in a few days. This scale and the distribution of latitudes determine the curvature of the world.
Each night thereafter, one of your bodies vanishes and adjacent pairs of simulated brains are merged into slightly bigger brains, animating the remaining bodies. Suppose for simplicity that there are initially five brain-scans, A B C D E; the next day there are four bodies occupied by AB BC CD DE in the same order. The mergers are weighted so that each original contributes equally to the descendants; this means that, in each pair, the one nearest an end counts more.
You have an opportunity to give yourself a happy second childhood.
At some point – perhaps immediately, perhaps after a couple of days when you have inferred some of the basics – the system interface reveals itself to each of you. I imagine a sparkling hovering teddy-bear saying, “I am your servant; through me the world awaits your commands.” You many stately pleasure domes decree …
Somewhere on your island is a portal whose other side is in the shared world (just one, contrary to some of my earlier notions), placed as described in that post. You can also invite your contemporaries to pop in anywhere.
When you first wake up, half of you (from alternate days) have switched sex; each day thereafter, you’re a boy if a majority of you remembers being a girl yesterday. Each evening you can vote to shift the threshold.