Enjin is a massive project, or at least seems to be one. It wouldn't be the first time a project is ripping another projects whitepaper or ideas.It does not necessarily make them a scam, but I wouldn't rule that out either. This is a very tough one to call.
I highly doubt it. They are a real company with a massive gaming network to leverage. cryptodevil accused them of being evasive about their company and network's statistics a few months back. In response, they provided the financials of Enjin Pte Ltd, which apparently all appeared in order, and contracts confirming the identities of contracted employees (who are associated with the ICO). He closed/archived the thread and dropped the accusations.
They have put considerable resources into the project too. I've looked into the project, and their vision/goals are definitely attainable. I'm not sure it's worth investing in (at ICO price or even considerably lower), but that's another matter. They did pay out a high-paying signature campaign and ran prominent ads on Coinmarketcap, among other advertising efforts. And their identities are generally public. If it's a scam, it's an elaborate one.