What's unsatisfying to me is when I can find holes in a strategy presumably concocted by a superintelligence.
I thought the obvious solution to the ending was gur gjb bs gurz jbexvat gbtrgure, fvapr gurl frrz gb or trggvat rkcbaragvny orarsvgf sebz pbbcrengvba vs gurl jbex unys gurve gvzr ba gur bguref cevbevgl vg jbhyq fgvyy or n arg tnva. Nyfb, gur onfvyvfx fglyr oenva fuhgqbja jbeq jnf pbzcyrgryl bhg bs gur oyhr ng gur raq.
http://www.infinityplus.co.uk/stories/under.htm?2. 15-30 min read time, rated "pretty good" by me.
There are a couple of interesting features of this story that I would like to discuss - but I don't want to introduce any spoilers, so I'll just leave this here for now.