I have never got past the second tower in Nebulus, in over a decade of playing the game on and off!
I usually start to play the game and play it many times in a row, learning how the towers work. I haven't completed the entire game, but I've managed quite a few of the towers. It is hard, but I wouldn't really go as far as saying it is one of the games one hardly can complete.
Games I really think have gone too far are Rygar on the NES, Mega Man VII on the SNES, R-Type Complete for the PC-Engine and the final boss in Phantasy Star II for the Genesis/MegaDrive. Man, what the heck where they thinking when they made the final bosses in those games?
In Rygar one has to replay WAY too much to reach the boss if one dies... and when the boss in itself is more or less impossible to beat, I just feel like throwing the controller into the TV-set.
In Mega Man VII one doesn't only have to play all of the eight regular robots first, and while 6 of them can be beaten while sleeping, two of them are just too frustrating and pure luck is what matters, it just seems TOO MUCH when finally reaching Dr. Wily... who, in turn, has attacks which are practically impossible to avoid and takes way too much damage, when oneself only can take 1 of his, 30 something, hitpoints each turn he attacks (and this is in his SECOND FORM, yes, he also has a first form to defeat). Ridicilous and makes the game seem completely worthless even though some of the earlier bits and pieces of the game have their moments.
In R-Type for the PC-Engine the final boss has two really huge rotating things which is attracted to ones ship and if touching them one is greeted with instant death. It took me like 50-60 snaps/reloads to manage the boss while running the game under emulation.
Phantasy Star II. Well. I got to the final boss without not that much trouble. Tried it and was smashed to pieces within seconds. Leveled up. Tried again. Was smashes to pieces within seconds. Kept on leveling up until it was way too time consuming to reach the next level (we're talking hours now) and still was smashes to pieces. Got fed up and used some action replay cheatcodes and maxed out all of my characters (they did reach their max levels), confirmed that I had all of the best weapons and magics and tried again. And, what do you know, I was smashed to pieces within seconds. So... once again, tried it under emulation, and realised that the final battle was based on pure luck. 90% of the time eveything went in the way of the boss, so by snap/reload I could go back before each of the attacks by the boss, making them eventually go in my favour... so, with way too much trouble and effort I finally got to see the ending sequences. I do not believe that there are many people out there in the entire world that have beaten this game without cheating.
In comparation Nebulus seems rather easy. Even though I haven't completed it, yet.
