I know this might inspire some people and p*** others off, but here's a idea that I would like to share with all of you. For Zombies there could be a weapon unlock system so that you earn experience, earn currency so that you can unlock weapons and buy them in order to add within the Mystery Box. For example, weapons that come at Level 1 can be a variety of Low Round Weapons such as Bolt Action/Semi Auto Rifles and Pistols and as you Rank up, you can earn more weapons, more attachments for all weapons (even wonder weapons) and traits to the weapons that makes them better. Below I thought of general guidelines on when certain weapons would be unlocked. Sub-machine Guns (MP5 for example) unlocked around Level 10-14 Shotguns (SPAS-12 for example) unlocked around Level 20-24 Sniper Rifles (WA2000 for example) unlocked around Level 15-19 Assault Rifles (Commando for example) unlocked around Level 30-34 Explosives (Claymore for example) unlocked around Level 5-9 Non-Explosives (Ballistic Knife for example) unlocked around Level 25-29 Light Machine Guns (M60 for example) unlocked around Level 35-39 Wonder Weapons (Ray Gun for example) unlocked around Level 50-54 Pack a Punch Machine (1st Upgrade) unlocked around Level 20 Pack a Punch Machine (2nd Upgrade) unlocked around Level 55 Pack a Punch Machine (3rd and Final Upgrade) unlocked around Level 90 Vending Machines (Quick Revive Soda for example) unlocked around Level 5. All of the types of weapons that can be unlocked will be spreaded out of availability throughout Level's 1 to 100 (for example the MP5 can be unlocked straight away on Level 1, but on Level 72 the UMP can be unlocked to use, so on and so forth) so that it gives the game itself more of a challenge towards it. For Wonder Weapons, obviously the Instant Killer ones such as the Thundergun, Wunderwaffle DG-2 and the Wave Gun would be unlocked around the area of Level 75 and onwards. Also you can choose the weapon of type in which you want to place within the Mystery Box. For example you can place 3 Bolt Action Rifles, 3 Pistols, 3 Sub-Machine Guns, 3 Sniper Rifles, 3 Assault Rifles, 3 Explosives (Primary Grenades not included), 3 Shotguns, 3 Light Machine Guns, 3 Semi-Automatic Rifles and 1 Non-Explosive Weapon. For Wonder Weapons, it will be locked for customizing within choosing them for the Mystery Box until the Top Level (Level 100) even if you have already unlocked the Wonder Weapon. For each weapon, they can have their own Level system up to Level 10 where you can purchase attachments, camos (Pack a Punch Camo would be fixed) and traits (for example an MP5 attachment can be Extended/Enlarged Mags, a MP5 camo can be Skeleton/Ghost Skin and a trait can be Unstoppable Bullets, same effect as Deeper Impact from COD WaW). For a weapon such as the Ray Gun, it can have a Dispersed Blast trait in which the Splash Radius is larger but the splash damage is reduced, or a Focused Blast in which the Splash Radius is smaller but the splash damage is increased. The attachment itself could be Dual Weld so that you have 2 Ray Guns and the Camo can be Blood Red. For Vending Machines, they can have their own Level System up to Level 5 on where the Perk itself is more effective of the default purpose it is set out for or/and unlock new features for the Perk itself so that it can acquire other roles as well (for example Speed Cola can be Leveled up so that weapons can be reloaded more quickly, and allows aiming down the sight to be faster and recover from down sight more quickly). There are many more ideas that I can come up with but it would take an eternity to enlist them all.