The checksum has nothing to do with the thing, whether the game works or not. A checksum is, as the name suggests, a sum to check. The thing to check is whether the bytes within the ROM result in a certain number. Changing one little thing in the ROM will change the checksum, so your Emulator says "bad checksum". A (virtual) machine like an Emulator for example is in no way able to tell you whether the ROM is corrupted or not. It simply follows the instructions given by the ROM's ASM code. The Emulator is unable to find out whether they make sense or not.
To make a long story short: Simply don't give a s*** about the checksum!
Also, your hack turns out to be... well...
not too good
I've tested the version you've sent to me (which is the same as you present here, no?)
Here are (quite a lot of!!) things, that bother me:
- Glitched Sprites
- Weird level design
- Monotonous passages (f.e. oversized slopes...)
- High, hardly reachable huge platforms with nothing on them...
- Bad Middle Rings
- Plenty of chances to get stuck
- Weird palette choice
- Bad animation settings
- Wrong Sprite-placement
- Wrong Object-placement
- Bad Warps
- Weird Camera-Scrolling
- Wrong Level-Entrance
- Second level suddenly stops at some point(???)
- Missing walls at the level's borders (especially in a castle there should be some!)
- Unusual spelling of level names
- Conceptlessness? (Linearity of levels, lack of puzzles. The question mark is there for a reason, that means I'm not sure whether it's true or not. If this really is just a Minihack, the first few levels must fulfill the conditions of more advanced levels already and that's what I'm missing. In a full hack (meaning 54 levels or more), it's obvious that the first levels don't have real puzzles and are linear)
And once again, I'm asking myself whether you actually test what you produce there.
Everyone
SIMPLY MUST, MUST, MUST notice, that there is something wrong with the passages presented in the following two screenshots, just to make an example.
1st screenie: Who would not notice the Shy Guy's wrong position?
2nd screenie: You need the cloud to proceed, so you must have seen it's glitched!
Assuming you really tested the levels, you simply must have played them blindfolded. I mean, missing a minor cutoffness is no big deal, but this?