When the AbstractChain level reaches gold, you can get an NFT for free, and you can access it from the homepage, which is similar to mining. Currently, you can receive 0.6 for free every day, DEPTH, the current price is 0.46. If you upgrade, you can receive 6 per day, and after further upgrades, 15 per day. Upgrading requires purchasing DEPTH and GBLUE; I only upgraded once, costing about 50U. If you don't upgrade, you can still go and collect every day, especially if you have many accounts! I feel that the purpose of my upgrade will give extra XP, and if you're worried about negative returns, you can just collect for free every day! I bought it when the price was 0.34 around noon!