It's a video game made by Konami, released only in Japan for the Famicom in 1990. The game is a spin-off of Konami's Castlevania series.
Enter - start (pause);
Arrows - move;
Z - jump;
X - attack; Esc = exit fullscreen;
You can change keyboard settings, save (F5) and load (F8) the game.
Put your mouse over the game and choose your settings, you can also play the game in fullscreen.