- Starting with a really minor one, but i think it would be nice to capitalize Mario's name in the intro message.
- The overworld feels a bit too square, and there are some perspective errors with the height of the landmasses in the main world.
- There's some serious problems with power-up balance in "Grasslands Castle"
The first room has 3 power-ups, being 2 of them right at the exit door (i even though that was a boss right away, but the door just leads to the Midway Gate...)
Then, in the second room there's only 1 power-up, so if we restart from the Midway, we get only 1 power-up to play the whole second half. (Also, i'm really not a fan of having that huge Firebar rotating around the power-up block! I'd like a safe environment to be able to get the power-up, as that Firebar killed me twice when i tried to collect the power-up)
Then, for the boss there are 5 power-ups! Being 2 before the door, and 3 in the boss room.
I get that you're trying to be generous (and the boss can be pretty tough), but it would be nice to balance the power-up distribution a bit.
- The first boss can become quite problematic! Basically, he only has one attack, which is spawning those balls that bounce off walls. The problem is that the balls do not despawn, and he just keeps spawning them until the sprite limit is full! This causes some serious lag, and can easily make the player overwhelmed
- I'm not a fan of how the Big Piranha Plants can just pop out of the ground in some levels of the Desert World with no indicators, especially because, unlike normal Piranhas, they pop out even if Mario is right above them! This led to a few surprise hits!
- In "Deserty Night", you used the same Bullet Bill Launcher graphics for all directional Bullet Bills! So it always seems they're going to shoot horizontally, until you see they're actually shooting diagonal/vertical Bullet Bills! This usually ended with me getting a bullet to the face...
- In the beggining of "Dark Pyramid" there's a single Koopa, and then a little bit ahead there's a power-up block on the ground, but if we kill the Koopa before seeing the block, we can't get the power-up!
- In the beggining of "Lava Desert" there's a upside-down lava pool right above the power-up block, so if we hit the coin block and make the power-up bounce, it gets stuck inside the lava pool.
- "Desert Castle" has more instances of dangerous sprites rotating around power-up blocks that i already mentioned in "Grasslands Castle". Again, i really don't like those, as i think we should be safe when we try getting a power-up.
Also, there's a blind jump
- The super fast vine in "Icey Cavern" really caught me off guard! I just pressed down and went right into the spikes below!
It would be nice to warn the player about these kinds of physics changes, as well as introducing them in a safe environment instead of a dangerous one.
- The use of Frozen Blocks in the Ice World is nice, but sometimes they can make us unable to progress if we lose the flower before melting the blocks (particularly in "Hypothermia Ice" due to the Shell Cannons)
- Also speaking about the Shell Cannons, i think they're too fast to react to right now. Not sure if there's anything you could have done, but maybe slowing down the Shells a bit would help. (or if there was some kind of indicator before they shoot. I know this isn't common with bullet bills, but these Shell ones are particularly unpredictable)
- The third boss is way too unpredictable! His attacks are too fast, and always come directly towards Mario! And also, the attacks are random, which is a problem because of 2 reasons:
1 - There's no way to know whether the projectile will kill us, freeze us or spawn a Goomba, so sometimes we might get hit because we try to dodge it, but the attack is not the one we expect it to be
2 - Since we require the boss to spawn Goombas in order to attack it, the battle length and our chances to attack it rely purely on the boss RNG.
These apply for all castles:
- It would be nice to have a Checkpoint before the Boss, as it takes a while to replay the whole second half of each castle to get another chance at the boss.
- Also, i'd recommend you try to define a standard usage of Doors, because pretty much every castle use doors in different ways, some use Boss Doors for simple screen transitions, and there's one in the second world that uses 2 normal doors.