Magento 2 Competition Panel allows you to build your own competition. This extension support multiple stores, hence you have numerous choice to build competition your own for different stores. Merchant can build two different kind of competitions like "review competition" (with the help of this competition your visitors/customers can submit a review of any product and able to participate in review competition) and "simple competition" ( in this competition visitors/customers just need to register their email and it permits to participate in simple competition).
The last order items are displayed as a suggested products in "review competition" so the user can use this item for review.At the end of competition duration, the system will auto generate winners for extensions & send discount codes which are configured by the site admin. It allows the admin to manually select a winner if preferred. Added email notification works for both admin & customers to notify for each update on going competitions.