It has 13 infection stages. However, if the 60 second timer runs out (continuous from level to level) then you lose.
I havn't been able to beat it yet, since for the later levels I can't seem to get what you need... an average of less than 5 seconds to complete the objective in each level.
Tip for first level:
Surface of your bridge should be flat. Use 2 steel supports off the bottom left starting point, one adjoining to the walk and one adjoining to the support structure underneath. THe support structure underneath should be an alternating triangle support system.
This is actually quite a good simulation system. Basically your joint supports are too weak to support the added mass of your structure, if all you do is spam connectors. This is what we call a HARD building game. Think about physics from high school.
Ragnorak?
I just popped it at the start of the level, used hunter's bow to AOE down the dragons. When they start shooting use a chalice to make yourself immune, and I was able to kill them all.
 "Infectonator!"){kind=icon}
 "Cargo Bridge: Xmas level pack"){kind=icon}
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