Is D Language mature for MMORPG Client ?

[Araq]

>> FSF's GNAT in GCC is GPL with linking exception, like the rest 
>> of GCC.
>> If you say "you can't build commercial software" with this, 
>> you can't build commercial software with GCC either.
>>
> Check http://libre.adacore.com/comparisonchart/

FSF's GNAT is not Adacore's GNAT ...
http://en.wikipedia.org/wiki/GNAT#License

> The program was written with Ada and failed in a most stupid 
> way.

It wasn't Ada's fault. The guys explicitely disabled some runtime 
checks. By the same logic you could blame the CPU they used ... 
Correlation is not causation.