It didnt take 4-6 hours. This took me about 3 days. I really liked the game, I wish you had a pipe module to keep wires really neat. If it were just 1 input and 1 output that would be great.
Another wishlist item would be a 3 input merger.
3rd, an upgrade that would make make splitters and mergers rotate priority between both outputs. if you had long chains of splitters or mergers, the top slot would take priority and could cause clogged chains down the line.
It was a really fun game, I liked that it had a realistic ending unlike other factory games.