In that case, the client has always been compatible (not binary compatible, but you can always download the latest version for no additional fee). It's that th

In that case, the client has always been compatible (not binary compatible, but you can always download the latest version for no additional fee). It's that the game changed beyond recognition over ten years. The simplest analogy I could give is - imagine that you started out playing chess, and ten years later the game was chequers. Each individual change was small, but they add up. You can still play 'something', but it's not what you bought, or perhaps more relevant what you invested significant time and emotional energy in to.