Jon Blow is very much the type of game dev that’s against using pre-made engines, and most of the time I feel like his arguments are purely poetic. He talks about how these engines are not efficient enough for “serious commercial” game development, and champions the self-made engine.
Needless to say, I’ve never really agreed with him on this. IMO most projects benefit more from the dev time saved by using a pre-made engine than from the near-perfect efficiency attainable through a  custom engine.
But this is a legitimate concern concerning Unity. Unity Webplayer games are uploading assuming they’ll be able to be played for a very long time, similar to flash games. But if updates in the webplayer kills compatibility for older unity games. Unity 2 games could have been released as late as 2010 or perhaps later. (Unity 3 was released in 2010) and now they aren’t playable in browsers at all? That’s only 5 years.Â
And I know from personal experience, importing Unity games from older versions into newer versions is a nightmare. There have been massive changes to monodevelops libraries and other systems in unity, so old code gets completely broken in Unity 5. So It’s not like the dev can just open up the old project and export it as a Unity 5 webplayer game. They’d have to commit a lot of work to piecing it back together.
So this is something to look out for if you’re working on a project in Unity. To be fair, Unity 5 allows for web publishing with WebGL, instead of using a plugin. Presumably this will fix this problem for at least new games going forward, but I’d expect any game made in Unity 4 or earlier will be unavailable through the web player sooner than the creators expected.
