Kof Theory Mercenary Screenpack 400 Slots Down...

You cannot manually type 400 lines easily. Use a MUGEN SFF/Select Manager Tool (like MUGEN Character Manager).

Usually defined in [Select Screen]:

cell.size = 25, 25       ; port size
p1.visible.grid = 10, 10 ; show 10x10 at once
p1.offset = 0,0

Make sure cursor movement wraps correctly:
In [Files] section, check sff and spr for page arrows. KOF Theory Mercenary Screenpack 400 Slots Down...

The standard KOF screenpacks usually cater to 40 to 60 characters (standard arcade roster sizes). However, MUGEN collectors often have hundreds of characters.

The 400-slot version is a fan-made modification (hacked screenpack) of the original layout. It expands the character select grid significantly while attempting to keep the portraits aligned. You cannot manually type 400 lines easily

Since direct links often break, here are the most reliable methods to get this screenpack working:

Symptoms: Screen flickers, lifebars don't appear, or characters float off the stage. The Cause: The screenpack was built for MUGEN 1.0 (640x480). If you are running MUGEN 1.1 (High-res/widescreen), the camera and zoom functions break the mercenary stage coordinates. Usually defined in [Select Screen] : cell

For years, this was the standard for "large roster" builds. But as characters became more complex (1.1 coding, high-res sprites), the old 1.0 version of this screenpack began to collapse under its own weight.