agile hill
Right now most people hoard their hexes for a new update. Once you have everything there isn't much incentive to keep opening.
However, if there were "Jackpot items" that were extremely rare and valuable that could be hit with any hex that would incentivize people to open everything. The Meatport soundtrack is a good start, but items like maybe a golden jacket, gold skins for guns etc.
You could have multiple "Jackpot items" running at the same time and you don't need to limit the minted amount, you can just make the drop rate so rare that it will stay low on its own. Then after a period of time the item is removed from the pool and whatever supply the items were minted up until then becomes the total supply forever. Making some Jackpot items more rare than others.
Let's face it, after the Jack O Hex event a lot of people are taking a break, rare items incentivize people to keep playing, and permanent rare item chances with every hex is the way to do it.