兰斯4.1 ~拯救药工场！~

This is a side-story in Rance series, released shortly after the fourth game, but dedicated to an entirely different quest. All kinds of troubles are happening to a factory where a new Happiness Medicine is being developed. The mercenary Rance is hired by the manager to investigate the source of these troubles. First task: clear the factory of the monsters...

This is a RPG with turn-based combat and strong adventure elements (menu with command verbs such as "Examine", "Talk", etc., at every given screen). Unlike the previous Rance games, the battles do not allow free movement on the screen, and are carried out in a more traditional Japanese-style way. There is no physical movement in the game; hostile areas (dungeons) are also explored by choosing menu commands. As in all other Rance games, there are explicit sex scenes in this game.

这是《Rance》系列的一部外传作品，于系列第四作发售后不久推出，但讲述的是一段完全不同的冒险故事。

在《Rance 4》本篇事件结束后的某一天，正在开发新型“幸福药”的幸福制药公司发生了一连串异常事件。大量怪物突然从公司的地下洞穴中涌出，工厂也因此陷入混乱。公司社长于是雇佣了身为佣兵的兰斯，希望他调查这些事件的源头。

兰斯接到的第一个任务，就是清除盘踞在工厂周围的怪物。由于希露因为工作原因无法离开家中，兰斯便带着雅典娜2号一同前往，开始了这次魔物讨伐行动。

本作是一款采用回合制战斗系统的RPG，同时包含较为浓厚的文字冒险元素。在几乎每个场景中，玩家都可以通过菜单选择“调查”“交谈”等指令来推进游戏。

与此前的《Rance》系列作品不同，本作的战斗中无法在画面上自由移动，而是采用了更加传统的日式RPG回合制战斗形式。游戏中也不存在直接控制角色进行物理移动的机制，即使是在存在敌人的地下城区域，玩家同样需要通过选择菜单指令来进行探索。

与其他《Rance》系列作品一样，本作中也包含明确的成人性描写场景。