Dogecoin (DOGE) was founded in the US in 2013 as a joke but quickly gained a large following. It became a popular cryptocurrency (DOGE) used for tipping the content creators (mainly on Reddit and Telegram). As the creators had no serious plans for their currency they didn't elaborate a roadmap and were not working on the improvement of their project too much. The founder of Dogecoin Jackson Palmer left the project in 2015.
Decentraland (MANA) is currently based on cryptocurrency Ethereum protocol. You can trade this digital asset on the fair number of exchanges. For example, Binance features MANA/BTC currency pair.