f4
Bulldog chess with Zombie (Evert823 - Arjun316694)

Yes, and I also believe that a lone zombie can probably force a mate against a lone king. A king can run, but at some point I believe it would be "frozen", then checkmated.
If anyone finds that I'm wrong (is there a way for a king to perpetually escape?) feel free to leave a comment. Maybe better to comment (here) about zombies to avoid cluttering this thread.
Board update is here:

Now that Arjun316694 hasn't made any move can I propose to add a Werewolf before we start?
https://www.chess.com/forum/view/chess960-chess-variants/werewolf-chess

Good point that a lone frozen king would be in stalemate. That means the game would end in draw, and so a lone zombie might not be able to force a checkmate against a lone king.
But since the side with a zombie would also have a king, maybe there is a way to force a mate, without causing a stalemate. So the status of menamedwert's question is:
1. Can (zombie + king) checkmate a (king + one other piece)? Yes, but it might not be forced.
2. Can (zombie + king) checkmate a (lone king)? I don't know.
About adding a werewolf to this game: I'll leave that up to Arjun. I don't have a werewolf graphic that matches this style, but can probably make one after I find some time.

Actually, I'm wondering if a lone zombie can force a mate. Wouldn't this example meet all the definitions of a checkmate? Black is in in check and since frozen there is no way to remove the threat, and so is checkmated. Correct?
35 ...Ke8-f8
36.Zd6-f6# (white mates)

Ok, this should be interesting. A game with three pieces which all have special abilities (not just special moves). Briefly:
1) Pieces in it's own army can move across a bulldog.
2) The zombie scares (immobilizes) other pieces.
3) The werewolf (by jumping) can capture two pieces in one move. Also a piece that captures a werewolf becomes a werewolf.
* Also a zombie can checkmate as shown in diagram above. This might be implied by the normal rules of checkmate, but since it can be subject to interpretation, it will be explicitly stated in the rules.
You guys will have a lot to keep track of in this game. I will add the werewolf in place of the queen, and all rules of the werewolf will be exactly as described in the link evert823 provided. Let me know if any comments or questions. Let me have a few days to make a graphic for the werewolf that's compatible with this board. This will be great to watch!

1. f4
Arjun316694, enjoy the game.
Once vickalan has made real nice graphics for the werewolf I'm happy to replace my temporary graphics.

Here's the board with werewolves that match the color-scheme of other pieces.
One clarification to rules: This game has no queens, so pawns cannot promote to a queen. They can only promote to rook, bishop or knight (same as in Werewolf chess).
Btw, this game is great!! The only way to make it better would be to add Frankenstein.
1.f4...g6
2.b4...Ra4
3.Zb3

Here's a template with all pieces, in case it's needed for any board updates. Fyi, I've recently switched most boards to 600 pixels wide. Using a larger image has no benefit because it just gets shrunk anyway when placed on this forum. If anyone has "old" larger graphics but would like the new smaller ones just send me a message.

A King can never be in check from a 'scared' piece, can he?
And one more thing to make clear: enemy zombies mutually scare each other?

A King can never be in check from a 'scared' piece, can he?
Awesome lego werewolf and zombie!
Based on simplest interpretation, and Arjun's comment (or lack thereof), a king is not in check by a scared piece.
Also two zombies attacking each other are both immobilized - like real zombies not fighting each other because they're too dumb and just stand there not doing anything.
Board update:
3.Zb3...Nb6
4.Bxb6...Ra6
This thread is for a game of "Bulldog Chess with Zombie" between Evert823 and Arjun316694. (Game results will be included in a player's score for the bulldog-series of games)
Game rules:
Board: 10 x 8 (see image below).
The pieces:
Guard (G) - Moves and captures like a king.
Zombie (Z) - Slides up to two squares in a rook's direction (cannot jump). The zombie "scares" enemy pieces with fright. All enemy pieces within its attack range are frozen and cannot move. Pieces remain frozen until the zombie moves, is captured, or blocked. Note that a king checked by a zombie cannot get out of check by moving - it can only get out of check by another piece capturing or blocking the zombie.
Bulldog (D) - Moves and attacks the same as a pawn, except pieces FROM ITS OWN ARMY ONLY can pass over it in any direction. If a bull dog reaches the 8th rank it can immediately move to any square in the first four ranks (but cannot capture a piece during this move). This move can only be completed during the same move it reaches the 8th rank. (If this option is not taken, the right to do so later is forfeited). The bull dog does not promote to other pieces as pawns do.
Board Setup:
Note the position of black's king and queen are switched compared to classical chess. This is so the guard and zombie are equal distance to each player's king and queen.
Castling:
The rules of castling are similar as in classical chess, however, with the board 10 squares wide, the king travels three squares rather than two. The rook finishes adjacent to the king (white: d1 or h1; black c8 or g8). All squares between the king and the involved rook must be unoccupied.
Other rules of this game are identical with rules of classical chess
Evert823 plays white.