Are there any alternative networks to Ethereum which are also being developed (which can compete) and can work in similar way in terms of storing and executing decentralized programmable code blocks? Which may for example deal with certain limitations in different way?
Rootstock would be the main example, check out their site for more info http://www.rootstock.io/
They use bitcoin instead of using their own coin, but they are not as far along with the smart contracts as Ethereum is, they just recently got their test net up.
Math.random()) that can cause Lisk sidechains to fork. The Lisk documentation suggests that you should not do this, but if you do, the damage will be contained to the sidechain and not effect Lisk itself.
Quorum is a Ethereum compatible private network modified to provide 3rd party observer abilities but still have private transactions.
Quorum™ is an enterprise-focused version of Ethereum.
Quorum is ideal for any application requiring high speed and high throughput processing of private transactions within a permissioned group of known participants. Quorum addresses specific challenges to blockchain technology adoption within the financial industry, and beyond.