"LOTS" of people better eventually find this review helpful.
!!! Ignore anything without a [-+> -+> ], if you think i'm being pedantic or hate old people !!!
-+> -+> TIPS/SPOILERS (though there is no real story like many of the old games)
Since no one has achieved Stage 4 in over 7 months I won't feel bad about posting this:
-+> -+> Stage 1 - Streets: xxxx
-+> -+> Stage 2 - Train: 3420
-+> -+> Stage 3 - Sewers: 5792
-+> -+> Stage 4 - Factory: 9203
-+> -+> Stage 5 - Lair: 3155
-+> -+> Stage 6 - Spacestation: 9692
-+> -+> BUG/FEATURE: Damage collisions that knock you back into a wall or, rarely, into the vertical middle of a platform will treat your final resting spot as an acceptable standing place. While this doesn't seem terribly exploitable in a run-n-gun, it becomes extremely useful on the final bosses AFTER STAGE 6 (holy hell...). Make sure you duck if you wish to remain in that position.
After playing this, I now realize the old NES games required almost a completely different skillset. Observation, pattern observation, timing, physics/detail scrutinization, observation x2, mental endurance/focus and constant self-reminders that "that challenge" isn't impossible (you're just missing something important, dummy).
(...and after finishing Cathode Raybits: "EXPLORE EVERYWHERE!!1!one!" Most of those old games took scavenger hunting to pathological levels. Duck Tales? Who the hell hides Ice Cream Cones and DIAMONDS in rocks. "LEAVE NO RANDOM OBJECT OR PIECE OF SCENERY UNSMASHED!")
And like most of the old games, once those things you're missing are found or realized, the game just becomes mainly a test of memory or focus (aka artificial difficulty or Nintendo Hard).
(Dissection of a difficult Jump) Jumping in B4A's conveyor crate Hi-jump, for example, becomes simple once learned/practiced and you'll succeed 4 out of 5 times.
-+> -+> Start as far back on the conveyor belt as possible (or as far back while still allowing you to successfully jump on top of the next crate) from where the crate drops so your jump angle, relative to the box, is lower. This gives you a little more time (nano seconds ARE a quantity of time, mother-fuckers) to place your feet on the box and quickly tap jump again. Start your jump when you see the next crate start falling. When placing your landing, don't aim for the far edge of the box but rather the center as you, hopefully, realize that your character doesn't remain stationary with the crate but rather the rest of the level and will immediately fall off, screwing with your jump. Once successfully on stationary ground again, immediately jump a third time because you are now standing on a mine that will blow your ass off and possibly knock you into the endless pit you just traversed.
I had more, but even I think that what i've written, so far, is too much...
The amount of detail that went into making this is subtle but is incredible and hopefully any newbies that read this might better understand the depth of thought that went into the design of the old games (because they were so limited in what they could do) and recognize some of that in your game.