Screen cut-off on NTSC Amigas
From Worms Knowledge Base
If you run Worms on an NTSC Amiga, part of the game screen will be cut off. This can also happen if you have a PAL Amiga but use an NTSC screenmode for your Workbench screen. But if you have the ECS Agnus or the AGA chipset (and virtually all Amigas have one or the other) and a suitable monitor or TV, then you can (and probably should) use PAL screenmodes.
WormsShell fixes this glitch by enabling an option to force Worms to run in PAL mode, restoring the NTSC setting when you quit back to Workbench.