Based on current data, "BPLNEX" appears to be a common misspelling of (Bepis Injector Extensible), a widely-used modding framework for games built on the Unity and .NET engines.
Many popular indie and mainstream titles rely on BepInEx for their modding communities. These include: BepInEx/BepInEx: Unity / XNA game patcher and ... - GitHub bplnex
For most games, installing BepInEx is as simple as moving its files into the game's main directory. Based on current data, "BPLNEX" appears to be
It uses tools like Mono.Cecil to modify game assemblies in memory, further reducing the risk of game file corruption. Based on current data