What about usecase of your coins and your blockchain at all?
SEM has 3 main use cases: it is a fuel for running decentralised apps, it used in governance and BFT consensus, it is a store of value and mean of payment.
Is this in theory only or coina are really using right now? Do they have any daaps on Semux blockchain so far? What is BFT consensus? Is this PoS or DPoS?
BFT consensus is not a PoS, it is rather an improved version of DPoS ,here is an article for a better understanding
https://en.wikipedia.org/wiki/Byzantine_faultno projects daaps have been launched yet , but work is underway

So people able to delegate their coins and get rewards here? How much ROI for delegating here?
Which works do you mean?
Yes, you can cast your votes for validators and get a reward, ROI is currently ~35% per year , but soon there will be a decrease in the reward for the block ,and the ROI will decrease, I mean the work to improve the platform
