Hey, I have an idea for one baby. He will be like a coward from PvZ, When the enemy is next to him, he hides in his hat. If he is eaten by a zombie, then when he dies, he will emit a fart 3x3, which pushes back enemies, and imposes poisoning.
The Binding of Isaac fangame, heavily inspired by Plants vs. Zombies · By
Good idea! I'm gonna try to think of the tainted counterparts of the four starter familiars you get in the game.
Brother Bobby: Shoots a lot of shoots but nearly no dmg (like soy milk)
Little C.H.A.D. : Produces less hearts but fights back
Cube of Meat: Has less health but splits into weaker Cube of Meats when killed (they dont split into more)
Bob's Brain: Explodes in a bigger range but deals less damage
The idea seems to be good, but here you need to think, because a banal improvement in the chances of a good store or heart is not interesting. It would be much better if the gameplay changed for each character in a coordinated way. And if you add, not as much as in Isaac. Because quality is better than quantity.
Hey, hello again! I have a cool unit design. He will be a "stone spectator" when the attacking babies shoot, he attracts most of the tears to himself and returns them, causing them damage. This works even for truckers. He cannot directly attack the kids. Thank you if you finished reading! Ps Lol, noticed one small jamb on the splice. Maybe I'll fix it later. 
Hi, again I have a good idea, the author of which is "Kapustinek". Alternative deck. I wasn't thinking about how to get it, I was thinking about one guy, just in case that idea was in the game. Sister Maggie - Shoots bloody tears, inflicts less than Brother Bobby, but when hit by an opponent leaves a bloody puddle that slows down and deals little damage, and disappears after 30 seconds. The rate of fire is the same. Here's the sprite and the GIF. 
I came up with a new baby. Brother Max. He has 1 unit of health, even a fly will kill him in a collision, but he has a shield, for 5 charges. When this shield breaks, Max emits a wave of enchantments that deal a bit of damage, and push all enemies to their starting point (Only works with those enemies that are on the same horizontal line as this kid). After this attack, the baby does not die, but remains until he is damaged. It costs 100 hearts, it is charged as much as the "Cube of Meat".
I threw some ideas and decided why not do something for locations…. well in the original game there are rooms well with water ,_,
you can also throw off your ideas for my answers, for example, water monsters or water babies.
(Upd) what is dark is deep water and what you see in the cells is shallow water.
Brother Polyphemus shoots huge tears, but he has a low rate of fire. Costs 150. Personally, I think that this toddler would be useful in many combos, but by itself it is not very good. For this, the price is low. 
Mom's shovel - replaces the usual shovel. It has two properties, the first of which was one discovered, mother's shovel digs a hole into which the enemy falls, and it closes, while giving 25 hearts. Second property: you can dig up one of the cells without dealing with a brother or monster. After ignition, a fossa in which a heart, a coin, a 5 coins, or a pill. But may nothing fall out. The hole is buried immediately after the object is lifted. Always damned, worth 99 coins. If a what, I translated it through a translator, so maybe there may be problems with the text. 
I have an idea for another good brother. Ghost Mask - worth only 100 hearts. It has two, even 3, new mechanics. It can only be put on another brother, while preserving the past properties of this brother. First, the mask can throw a chain, and pull the enemy to itself by 1 cell. It can do this if the enemy is no further than 7 cells, and no closer than 2. The second is complete invulnerability to the attacks of absolutely all enemies. Enemies who approach the brother with a mask, just pass through without causing damage. Mask can kill shovel only or "Altar of Sacrifices". Переведено при помощи Google translator.
Or what if:
1: it could throw itself and bounce off the enemies while slowing them and then respawn and wait a lil bit to throw again
2: it would act like the grape thingys from PvZ2 where it would explode into shards what whould bounce through the field hurting enemies but it would kill itself in the process.
and 3: it could be placed and you, the player/isaac could push it to hurt the enemies
The challenge seems cool btw.
