Let's start off with the most painfully obvious of all these common elements: the first-person shooter gun progression. It's present in just about every standard first-person shooter and follows almost exactly the same rules every time. And there's a reason! It's good balance as well as maintaining an effective cool-to-effectiveness ratio (I just made that up!). The progression, in most cases, follows this:

• Melee Weapon: You hit guys with your sword/crowbar/boot until they die. Tends to be powerful but slow and unwieldy as well, making the player seek out anything they can to take care of distance combat. In most cases, it's the player's last resort. Gordon Freeman's crowbar and Duke Nukem's kick are classic examples. For a different example that actually encourages the player to get it thanks to its ability to close gaps is the energy sword from Halo.
• Pistol: Slow, weak, and limited ammo. This is your basic weapon and you get it very early on, sometimes even before the melee weapon. In most cases it is discarded in favor of a more rapid-fire or stronger weapon, but can also be extremely deadly in the right hands, especially if the player can get headshots with regular frequency. Halo, Half-life, and Doom are all good examples of the pistol in action.
• Shotgun: Slow but strong and with limited ammo. These is a staple of every single first-person shooter, and it's for a reason. Firing a shotgun is very satisfying! This is the first real weapon that players will continue to use after getting better weapons because of its close-range lethality. Shotguns can range from the mundane (like Halo) to the strange (Unreal's flak cannon)
• Machine Gun: Chaingun, pulse rifle, whatever you want to call it. This is the first rapid-fire weapon and, much like the shotgun, will be a staple of the player's arsenal. Used for those pesky groups of enemies. Do I really need to give an example?
• Explosives: Here's were it diversifies a little. The explosives category is the "big guns", as it were, and do everything from take out tanks to blow players into bloody chunks. The classic rocket launcher is a good example of this, but it can also be things like grenades or mines. If it explodes, the player will get it right about here.
• Special: Welcome to the strange side! Here's where designers actually decide to get creative. Weapons in the special category fit a very specific purpose and are often left completely out of a game. Sniper rifles, energy cannons, lightning rods, and disintegrator beams all fall into this category. These are the most powerful weapons in their particular field, and more often than not, saved for last.

In any single-player game, the weapons will usually be distributed in that order, starting with melee and ending with special. For multiplayer games, this list acts as a sort of "desirable weapons" list, with players seeking special weapons first even if a simple shotgun would do much better.

In RTS, tech trees follow a similar structure in how powerful units become over time. This progression applies to both when in a campaign you get the new units as well as when in a multiplayer game you get them as well. It's a fairly simple list!

• Basic Infantry: These are your grunts, footmen, soldiers, and conscripts. They are often armed with little more than a machine-gun or sword and the determination to fight. Cannon fodder away!
• Strong Infantry: These are your demomen, rocket soldiers, and in the case of fantasy games, your bowmen and basic magic users. These guys dish out the damage, but can't take any at all. Used in very certain situations (such as a vehicle or cavalry rush).
• Basic Vehicles: These are your jeeps, light tanks, light cavalry and supply carts. They are more mobile than infantry but are a larger target and much more expensive. Explosive Infantry are usually the counter to these guys (for a while).
• Strong Vehicles: Your medium and heavy tanks, submarines, destroyers, wolf riders, and knights. These guys are tough and dish out damage, but are very expensive and usually have a specific weakness that can cripple them.
• Tech Upgrade: Time to upgrade! Whether this means enhancing your fort or building a research lab, you almost always have to do it right in-between strong and the special.
  
• Special Infantry: Oh boy, these guys are what you play an RTS for! Spies, sorcerers, commandos, and demons all fall into this category. They are strong and tear up stuff like crazy. In some cases, they are the single most powerful unit in the game!
• Special Tanks: Your experimental units like cloaking tanks, dragons, or crazy laser-shooting walkers all belong to this category. Unlike special infantry, these vehicles often cost less so you can make them more easily, but aren't as (singularly strong).

An RTS is all fine and dandy, but what about RPGs? Well, they are guilty of the same thing. Weapons range from wood to glass and usually follow a very strict linear power progression. It's not worth discussing in detail because it's little more than, "Oh hey, this weapon is steel instead of bronze! I should use it." Both American and Japanese RPGs are guilty of this (looking at you, Bethesda!), but there are a few that go outside the norm. Possibly the three games most guilty of this linear equipment progression are Chrono Trigger, Oblivion, and Diablo. Where are the options?!

As you can see, in most cases these common gameplay staples are a good thing, as they simplify the balancing process. But there's also an element of drudgery about this whole state of affairs. What if you made an RTS where the special units came first and basic units last? Or a shooter where a pistol is the best weapon in the game? Or an RPG where every piece of equipment is worth hanging onto? Even just a simple change in these basic genre gameplay progressions is a breathe of fresh air to those that find it, and it's worth keeping in mind when designing your own game.

For more coverage on indie games and the scene, keep an eye out for Indie Showcase at the same bat time, same bat channel. Also check out Freeware Friday and our indie category for some excellent freeware games and indie news, respectively.