This is a cool submission ! I wanted to show you the great city I built, but the game crashed when I alt+tabbed... :( I had great fun though !
The really strong aspects are the atmosphere and soundtrack, which is very catchy despite its simplicity, and charming graphics and UI. It all runs very smoothly and building is a pleasurable experience. Overall the esthetical experience was well executed.
The concept is really original as well, so I'd like to make some remarks about the game design :
1. The game seems to point to the Reactor as the reason why the player should accumulate resources : upgrade the reactor, go faster, get there quicker. However : - speed does not affect anything other than the time of arrival - survival solely depends on the ability to re-build the island, not on speed - the ability to re-build the island (blocks) costs the same resources as upgrading the reactor, which is really expensive
This all makes upgrading the Reactor a really poor choice, despite it being central to the island. A far better strategy is to never touch the reactor, and build rows of resource-producing buildings until you can re-build the island faster than it falls. Then, speed never matters again.
This could be avoided in two ways : either remove the Speed mechanic from the game altogether, and increase building/abilities diversity, or make it have some crucial importance during gameplay. Maybe speed gives momentum which holds the island together ? Or it makes resource buildings function faster ?
2. Energy and metal are different names for the same element : a resource you accumulate every second with buildings, and that is used to build more buildings (I am aware that the reactor costs energy only, but its cost is negligeable). Maybe both resources should vary more.
I am aware of the time constraints though, and this is very well done for a 3-days (solo ?) game. Congratulations !!