more people are mining and difficulty increased

2000% in half a day? That would mean someone with a lot of hash power joined for a while. I assume he'll switch to another altcoin again later.
Hi all nobtcoi community, bitcointalk mod have closed nobtcoin airdrop thread. I will figure out new method to run the airdrop as soon as possible.
Read this:
Most giveaway threads are no longer allowed in the Alternate cryptocurrencies sections. From now on, posting or replying to such threads could result in being banned. Existing threads will be locked.
Specifically, you are not allowed to give people any incentive to post insubstantial posts in your threads. You can't offer to pay people who post their addresses, usernames, etc. You can do giveaways off-site and link to the giveaway page in a thread, but you can't give people any bonus for replying to your thread.
mprep also have a response regarding a similar situation of lizicoin coin here:
Giveaways that requires posting in a thread are no longer accepted due to numbers of spams it can recieve when people starts claiming.
Instead, maybe you guys can make a doc sheet and collect data (nobtcoin addresses) of those interested to get some coins from the airdrop.