Soviet Jump Game (Dendy Hoax)
The "Soviet Jump Game" advertised on the Game Grumps channel is 100% a newly game, and the story of its origin as an unreleased game for the Dendy console is a marketing hoax.
On November 16th 2019, the Game Grumps channel uploaded "Russian BOOTLEG Nintendo games!" where Arin Hanson tried to play several bootleg Dendy cartridges on a Retron 5, with most failing to work.
One of the included games was this cartridge, labeled in hand written Cyrillic.
When booted, it showed only an error screen, showing a Dendy console and what looks like an acoustic coupler, with a blinking red X between them
The next video was "MORE Bootleg Russian Games!" (posted on November 24th, 2019) where Arin & Danny play some more games for the Dendy, again showing the cartridge and the error screen.
On December 3rd, 2019 the video "Lost piece of gaming history UNCOVERED" was released.
In this video, Arin finds out that the game needs an Internet Adapter, buys a serial-to-ethernet adapter, shows a russian commercial for an internet-enabled Dendy, gets the game to partially boot, gets his friend Thom to dump the ROM, and is told it's an incomplete battle royale online multiplayer game for the Dendy, and then announces they're gonna revive the game and provides a site to sign up for the beta. (This is the video that people have trouble with)
The next day, the trailer for "Soviet Jump Game" was released on the Game Grumps channel. This shows the game footage for the revived version of the game.