why is coop 1 hour longer then solo
Effort mainly. I put hundreds of hours of work into my solo run and no one (myself included) has put that much work into co-op.
Additionally the netplay has a tendency to desync which means a lot of the tricks are very inconsistent in co-op. There are ways around this though (Using Proton or Steam Remote Play, or just being in the same room as the person you're playing with).
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