User blog comment:Visually/RnD is hard and expensive. But you can do it only for rewards./@comment-27267536-20151211125813/@comment-26536836-20151223141044

If someone has tons of credits and all the pro cards, it won't be that hard but still have to play it like every 10 to 15 hours per day.

Engine cards are extremely hard to get. So it actually extremely hard, I think.

So not many people have chance to complete, I guess.

This new update's (Santa's Gift Update?) RnD also tough like this one, I think. And so many people will waste their credits and tokens again, probably.