We actually looked into this, both as DLC, and as Steam Inventory Items. There was a few reasons. The first was doing it as DLC, Every individual store item would need to be an individual DLC. You can’t ever remove them, or they stop working (and some other issues that arise in removing them), which means if you can imagine many years down the road, that’s going to be an extremely long list of DLC’s. The next issue we found was that in-game currency can’t be used to purchase DLC’s on Steam, which means all the currency coins we previously issued couldn’t be used, which we won’t do. With Steam Inventory, it had the same issues as being offline, in that they require an internet connection regardless to verify, so wouldn’t get any closer to working for a true offline mode.