Files with bndl extension can be generally found as Bundle format files from games, like F.E.A.R.
Software that open bndl file
BNDL file extension - Bundle file format
What is bndl file? How to open bndl files?
File type specification:
File extension bndl is associated with bundle files, archives used in some applications or computer games, like F.E.A.R. and others used LithTech video gaming engine developed by Monolith Productions.
Also used by Need for Speed Most Wanted video game from Electronic Arts, but that appears to be completely different format, just used for the same purpose.
The default software associated to open bndl file:
Company or developer:
Monolith Productions, Inc.
F.E.A.R. (First Encounter Assault Recon) is a psychological horror first-person shooter developed by Monolith Productions and released in 2006.
Need for Speed: Most Wanted 2012 
Company or developer:
Electronic Arts, Inc.
Need for Speed: Most Wanted 2012 is a car racing simulation computer from the popular game series developed by Electronic Arts.
List of recommended software applications associated to the .bndl file extension
Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open bndl file, edit bndl file, convert bndl file, view bndl file, play bndl file etc. (if exist software for corresponding action in File-Extensions.org's database).
Unspecified and all other actions for computer programs working with bndl file - Bundle file format
Click on the software link for more information about F.E.A.R.. F.E.A.R. uses bndl file type for its internal purposes and/or also by different way than common edit or open file actions (eg. to install/execute/support an application itself, to store application or user data, configure program etc.).
Microsoft Windows:
Main software associated with bndl file by default:
F.E.A.R.
Need for Speed: Most Wanted 2012
