1. A system for online gaming including virtual placeholder items in an online game, wherein users can exchange the virtual placeholder items for virtual items of value based on user achievements during gameplay in the online game, wherein the users are associated with client computing platforms, wherein the users include a first user associated with a first client computing platform, the system comprising: one or more physical processors configured by computer-readable instructions to: execute an instance of an online game, and facilitate interaction of the users with the online game; manage inventories associated with the users in the online game, wherein the inventories include a first inventory available to the first user; provide a first placeholder item to the first user such that the first placeholder item is included in the first inventory of the first user, wherein the first placeholder item can be exchanged based on one or more user achievements in the online game, wherein the first placeholder item can be exchanged for a first set of one or more virtual items of value that are useable in the online game; provide a second placeholder item to the first user such that the second placeholder item is included in the first inventory of the first user, wherein the second placeholder item can be exchanged based on the one or more user achievements in the online game, wherein the second placeholder item can be exchanged for a second set of one or more virtual items of value that are useable in the online game; determine a first measure of performance achieved during gameplay in the online game by the first user; determine a second measure of performance achieved during gameplay in the online game by the first user; and exchange the first placeholder item for the first set of one or more virtual items and exchange the second placeholder item for the second set of one or more virtual items, such that: responsive to the first measure of performance being greater than the second measure of performance, the first set of one or more virtual items has greater value than the second set of one or more virtual items, and responsive to the second measure of performance being greater than the first measure of performance, the second set of one or more virtual items has greater value than the first set of one or more virtual item.