Microsoft Treasure Hunt

This achievement requires purchasing 5 Heart upgrade.

Upgrades can be offered for purchase in the Mummy Shop which comes after level 1 and then after levels that end in 5 and 0:
The Shop will always offer individual use Pickaxes, Dynamite, and Maps in addition to the Amulet of Rebirth and a random item that can be any of the upgrades you currently need (Pickaxe Belt, Dynamite Bag, Map Tube, the 4th/5th Heart) OR a pack of shields, as seen here. Upgrades are kept when you die so you can work on them over multiple runs through the game.

Upgrades build up somewhat consistently. The 5th heart costs 128,000 gold and is one of the final upgrades you can get- you won't be offered it until you've nearly maxed out your Pickaxe Belt, Dynamite Bag, and Map Tube (at 30 each). You'll also need to have bought the 4 heart upgrade for (IIRC) 64,000 gold.

I had an issue where the game would get stuck in a loop where I was only offered packs of shields and never upgrades that I got out of by resetting app data and only playing offline. During my offline-only playthrough, I was only offered packs of shields a few times and I never got stuck in the loop. Also, you see zero annoying video ads while playing offline.