Screen clock c# - it can show you unpaused time from round start
Without it you won't know time cost of your decisions

Sellable Submarines - Allows you to sell your subs
Subs are ridiculously overpriced on higher difficulties in compare with other upgrades
This may be ok in vanilla, but when you need to outrun radiation it forces you to stay in dugong until The Great Sea
I think this is the most natural solution for that

Fast Forward - allows you to speed up the passage of empty spaces in single player