Yosaku ((NGP), on The King of Fighters: Battle de Paradise (NGPC) ROM, in NeoPop (PC))
Yosaku, the hidden black and white game you get if you put the Neo Geo Pocket Color color game cartridge of SNK’s game “King of Fighters: Battle de Paradise” in a black and white Neo Geo Pocket system; I’m using the old emulator NeoPop to achieve the same effect.

Figured out some stuff, particularly about the boars who rampage at your woodsman: their timing is consistent, so if I follow my pattern and am prepared at the right time, I’ll be ready for the boar attack. Now I just gotta get better at not swinging and missing. = oo
Between my last Yosaku outing, in 2018, and now, there’s been an informative wiki page made: Yosaku | SNK Wiki | Fandom
(I had forgotten my dates, it was '79 for the arcade version, and '81 for the Epoch Cassette Vision version.) Apparently the arcade game was based on a “popular song ‘Yosaku’ by Saburo Kitajima,”
(non-embeddable version w/ English translated text: https://www.youtube.com/watch?v=vx2FN49yIsk )
even including the melody in the arcade game. And the Epoch Cassette Vision console version made in '81 was an unlicensed version!
Yosaku’s arcade title screen “OLCA CORPORATION” seems likely to have been a typo for Orca, a Toaplan predecessor; Orca evolved into “Toa-Kikaku Toaplan” (“Far East Project”) from Orca and did some work for SNK. Hm wait what did they do?
Okay well all I can find is one game, “Jong Oh” Jong Oh | Toaplan Wiki | Fandom (or “Jongo” says Wikipedia Toaplan - Wikipedia ), a 1984 arcade mahjong game, developed by Toaplan and published apparently by SNK.
SNK’s full name is Shin Nihon Kikaku (“New Japan Project”), and they don’t usually spell it out anymore but they did on the Yo-Sa-Ku title screen on NGP, maybe as a call-back to Orca and Toa-Kikaku Toaplan and the original arcade Yosaku game.

Jeremy Parish has an extensive video about the Epoch Cassette Vision (biggest Japanese console before Famicom, the video says) bootleg of Yosaku: https://www.youtube.com/watch?v=cdUDvoGFp8s (“Kikori no Yosaku,” which translates roughly as “Woodcutter Yosaku,” according to Yosaku (lost arcade game) | Forums - The Lost Media Wiki , which also talks about yet another unlicensed console version, for the Sharp X68000, and later remakes/bootlegs–among which you could count this hidden NGP minigame, I suppose! But there’s also like this Famicom Mario romhack Romhacking.net - Hacks - Woodcutter Yosaku Family Basic Demo version trying to re-create an earlier romhack:
).