Undeadline

is a 1989 vertically scrolling shooter video game developed and originally published by T&E Soft for the MSX2 home computers. It was later ported to the X68000 and Mega Drive, published by Palsoft, followed by digital re-releases for Microsoft Windows. Both the MSX2 and X68000 versions also received physical re-releases by Japanese retailer BEEP. It follows a group of characters in rescue of queen Althea from Zidane, a kingdom surrounded by barriers connected with the demon world, whose monsters have overflowed it. Controlling either a fighter, wizard, or ninja, the player can choose from six stages and play them in any order, fighting against waves of enemies and bosses, while defending or avoiding collision with their projectiles and other obstacles.

Undeadline was directed and designed by Tokihiro Naito, who previously worked on Hydlide and Hydlide 3, with Tetsuya "Futaro" Yamamoto serving as main programmer. The soundtrack was composed by Kazunori Hasegawa. Due to T&E Soft liking to push its playtesters to the limits and as their skills improved naturally, it led to the designers increasing the difficulty to keep up with them, particularly paying attention to both enemy movement and spawn patterns. Because of its rarity, original copies of the MSX2 version commands high prices on the secondary game collecting market. The game received generally favorable reception from critics, most of which reviewed it as an import title, although its difficulty has been criticized.