Could you refer to my profile comment and look for key that follows "HNZPJ0"?
You can download "HNZPJ0" project with the key, and please try running "HNZVTS" or "HNZVCS" in downloaded project.
As Pkyoshi19 has said, a subroutine which can be called by GOSUB has to be followed by RETURN.
RETURN removes a program counter which has been stacked by GOSUB from memory. However GOSUB without RETURN keeps memory stacking and stack overflow will occur soon.
そうですね、私なら次のように書きますが、正しいかどうかと言われると、自信はないです・・・
You need additional purchase DLC to play this game, but currently it is available in Japan only.
(このゲームをプレイしていただくためには、追加有料ダウンロードコンテンツが必要ですが、今のところ日本国内でのみ有効です)