All 12 of the classic Marshmallow Duel pickups have been reproduced in Mowbray's Revenge, and there are 6 all new pickups which have also been created for the game.
Pickups are spawned into a map by Pickup Spawners, which are fork shaped metal objects. Each pickup spawner may have its own unique settings defining what types of pickups it will spawn, at what speeds and how often it will spawn, etc. However most spawners are default, and will spawn pickups at random from those chosen from the mduel menu when creating a game, and the amount spawned will depend on the pickup multiplyer set on the same screen. This allows you to control how easy/hard it will be to get pickups by allowing less or more pickups in the game. It is generally a good idea to go with a multiplyer of 3.
In the game, after the pickups are spawned, they will float around the map in purple bubble things. You have to jump around and try and catch the pickups, and once you touch one you will have that weapon. You can only have one pickup at a time, and once you have used it, and run out of ammo (if the weapon has more than one ammo) you cannot use it again, and have to catch a new pickup to use anything. Catching a new pickup will replace your old one, so you have to be careful not to get too close to unwanted pickups. Especially if it is a skull, which will murder you.
Following is a list of all the pickups in the game, linking to their description in the pickups strategy section.
Classic Pickups:
Registered Version Pickups:
Mowbray's Revenge Pickups: