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There's actually 8 more NPC's that we didn't knew about. It's NPC-293, NPC-294, NPC-295, ... , NPC-300. Normally, those NPC's are invisible, but you can make them visible by inserting a graphic. Of course it must be in "GIF" format.
By that I mean this:
- Spoiler
To place these NPCs in an SMBX level, you should use PGE Editor, as SMBX Editor doesn't have any slots for them.
Those NPC's are all the same. I mean they have same behaviours.
For example, they can be freezed, but if you'll unfreeze them, they won't move:
They can walk on lava(!):
They can't be defeated by Peach's Heart Bombs, Link's Lasers, Toad's Boomerangs, Mario's/Luigi's Hammer's and Fireballs:
They can't be defeated by Rainbow Shells:
They can't walk on Switch Block's Outlines, but can walk on Switch Blocks:
Down below there's a second part:
Added after 10 seconds:
Also, you can die/lose your power-up, if that NPC will touch Clown Car:
Note: you can't defeat those NPC's by a Clown Car.
If your buried Hammer Bro will throwing those NPC's, they still will be able to walk on the ground and they won't defeat each other:
Those NPC's can't be defeated by Veggies, Mushroom Blocks, Pot Piranha Plants, Bombs and even by Metal Pipes (Metal Pipes will just push those NPC's):
If NPC will stand on a hittable block, you won't be able to defeat it:
Those NPC's can't be defeated by SMB3 Ice Blocks and player's Ice Blocks:
Also, if you'll try to kick some NPC on those secret NPC's, kicked NPC will defeat itself:
You can't defeat those NPC's by a Boot, by Link's Shield, by jumping on them and by spin-jumping on them.
Those NPC's can also walk on platforms:
Also, those NPC's are very fast.
NPCs after 300, like NPC-301, NPC-368, NPC-3360 or NPC-368687 will crash your SMBX (except for NPC-302). You'll get this error:
There's also another secret NPC - it's NPC-0. Well, it actually doesn't do anything, it doesn't hurt you and you can't even see it.
Also, I didn't tested all those NPC's with a Notepad, maybe they have more behaviours. I will test them with Yoshi and Koopa Shells tomorrow.
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There's a wiki page for these NPCs now!
http://wohlsoft.ru/pgewiki/Dummy_NPCs_(SMBX)