I love zero missions, its the 3rd best game in the series for me (behind prime and super, which both rank up within my top 10 games of all time)
I'm a gigantic metroid fan, so that might have a little something to do with it.
i went through it on normal first.. 3:30 78%
then i managed to beat it on hard last night 100% 4:15
On hard, each energy tank is only +50 max energy, every missile pack is +2 missiles, super missile/powerbombs are +1 each, you do less damage and you still take double... makes a few areas of the game amazingly difficult.... but sadly, not enough.
some of those endings are going to be insane to get (under 15%? O_O)
but, i'll try for them anyway, cause i know i'll play through this game probably over 20 times without a doubt. (I've been through fusion far more than i should have)
i do have some issues with the game, but not many.. the large portion of them revolve around how i feel the world map is FAR too *cramped* i prefered the (seemingly)huge, sprawling maps of metroid, metroid 2, and Super Metroid, perhaps its just becuase this game seems to have every single room with a purpose that it seems cramped. Also there are far less super missiles and powerbombs to pick up, so 100% though still difficult, wasn't nearly as long and exploration based as it should have been.
Anyway, R&D1 has definately got the feel of what a metroid should be. This metroid controls the best out of every metroid game ever, and if they could apply some of the newer controls along with a few more tweaks in level design, they could be well on their way of making a metroid game superior to Super Metroid....