As Alex wrote in his review, Opus Magnum is one of the most satisfying puzzle games ever made, and you're given plenty of freedom to solve its alchemical, machine-based puzzles the way you want. It's made by Zachtronics, so if you enjoyed the likes of SpaceChem and Shenzhen I/O, you'll love it.
Tropico 5 is less spectacular, but it's still a solid city builder that lets you play as the ruling dynasty of a banana republic. If nothing else, it's a chance to reacquaint yourself with the series before Tropico 6, which is due out early next year.
As a reminder, EA's basic Origin Access costs $5/£4 per month or $30/£20 per year, and gives you access to free games and limited trials of new titles. EA launched Origin Access Premier in July, which costs $100 a year, netting you full access to new EA games when they come out.
The other games coming later this month are: