Mechanically Disinclined

You've got a fantastic game idea, don't you? Listed all the things you want to be in it and put in a little planning, right? Maybe you've planned the maps and resources needed as well? Now you are just sitting there, wondering where to start. Enemies, crafting, inventory, which mechanic should you start upon?

The place to start in any major project is the foundation. In games, that would be the core mechanic. There are several types of mechanics in games, core, supporting, challenge, and extra/other. I'll go over these mechanics so you can better identify them and choose the actual core mechanic.

Core mechanics, although there is usually just one, are used throughout the game; or to beat the game. Minecraft is obviously crafting, since you have to craft tools, weapons, and armor to progress. Mario games have Mario's base moveset (jump, punch, kick) as the core mechanic. Fighting games have character movesets as the core mechanic. Can you guess Pokemon's core mechanic? It's not capturing, but battling. You have to battle to progress or win the game, like any base RPG, but capturing is needed to get more characters to battle with. Capturing is a support mechanic.

Support mechanics are used to support the core gameplay. Minecraft has mining. You have to mine wood to get materials to craft tools for more mining. Mario usually has support pickups (mushroom, fire flower, tanuki) while most fighting games just use the core mechanic. With Pokemon, capturing is the support mechanic to get characters to battle with (no capture nuzlocke anyone). Most challeng mechanics are used to control the games pacing or make it more fun. If you could just beat Bowser without collecting the macguffins and unlocking the worlds, Mario games would be boring.

Challenge mechanics are used to give the player a challenge. For most games, this is usually the enemies you fight. Sometimes the challenge mechanic is a support mechanic as well, like in Pokemon. Minecraft would be even more boring without the mobs to kill, but it would still be nice to explore. Timers, puzzles, goals, and achievements are usually challenge mechanics. Anything that is used to determine/cause a losing scenario is usually a challenge mechanic. Player stats are a great example of a simple challenge mechanic.

Now for the final type of mechanic. Extra/other mechanic usually don't affect gameplay much, but it can add to it. For Pokemon, the trading mechanic is extra. All the Pokemon could be in a single game, but trading was added to expand the game. Similarly, items in Super Smash Bros. and Mario Kart are extra (but fun) mechanics. Wile these extra mechanics add to the game, too many can bog down the game or expand development times (going to ludicrous dev time). If it isn't a core or support mechanic, work can usually be delayed upon it.

Some things to consider about mechanics. Some games are just a core mechanic (fighting games). The advertised mechanics are not always the core mechanic (pokemon). Some games can have either two core mechanics, or core/support symbiosis (minecraft) where the core and support mechanics work together to hold up the game. Core mechanics can also support other mechanics. Extra and challenge mechanics should be the last worked on and the first to be cut. Online play is almost always an extra mechanic. Inventories are almost always a support mechanic.

You should almost always work on the core or support mechanic first. As a developer, you can give yourself the macguffins needed to use the core mechanic. Unless the core mechanic really needs a support mechanic, start with the core mechanic. Mechanic don't have to be perfect, just working; polish can come later.

Little One just had two main mechanics when I started, the vacucell collector and farming. Item collection was the core mechanic and farming was actually supposed to support a challenge mechanic. Those were the first two mechanics I started with.

Blue Bloom has several mechanics, more than Little One. I was confused at first what mechanic to start upon, but crafting will be the core mechanic. Resource collection will be a support mechanic with the flora and fauna being challenge mechanics. In fact, Blue Bloom will have several challenge mechanics.