A fighting game with shifting movesets, in a three-layer approach.
Layer One: Base CharacterYour base character determines what "archetype" you follow- are you light and fast, are you slower but have better reach, are you heavy and powerful? Some archetypes are special- you have a separate gauge to manage, or maybe your SP goes up naturally. Maybe you have different modes.
Choosing a base character gives you what your basic attacks are- light, medium, and heavy strikes, but none of your input moves are there yet. I'll make three different characters on this system, as examples.
Let's take a mode-changing, light, fast character. Their normal mode has poor reach, but they're fast and able to strike well in the air or on the ground. They lack in defense.
Changing mode gives you better reach and better damage, but you must charge this mode up through a separate gauge. You have to charge via a move that leaves you vulnerable.
Let's make ourselves a midweight, with good reach at the cost attacking speed, and good damage- our attacks are somewhat slower than other characters, and don't have the invulnerability frames we need to avoid getting hit if we bring out a strong attack from the start. We're also not great in the air. Our average-overall, good damage potential build shines in that once a combo is started, the momentum will carry us through to a strong finish for a good deal of damage.
Let's take a character with a Heat Gauge. Let's say, a midweight with high mobility but sacrificed damage, that's otherwise average. The Heat Gauge is a limiter- allowing us to pull more power out of attacks, so long as we don't overuse it and overheat.
Layer Two: Natural SkillsNatural Skills determine what special attacks that don't eat from the SP gauge and other attacks useful in comboing are capable of. Different styles of attacking- aireal chain characters that throw enemies into the air and keep them there, groundhogs who own the floor and can trip up anyone who thinks otherwise, characters who use projectiles in all their forms, and anything else that can be done without eating the SP gauge goes here. In the examples...
Let's add Dash-Aerial to our mode-change build. Now, we're able to follow and keep attacking any enemy unfortunate enough to face us in the air, and we can dash back and forth further than others. When mode-changed, dashing does damage and knocks anyone hit into the air, allowing us to really sink our claws into them while we have the chance.
For our striking midweight, we'll add Linear Projectiles: Versatile. This will give us anti-air and forward projectiles, allowing us to catch an unsuspecting or aggressive enemy off-guard and open up some combos, at the expense of not being able to do anything special with the projectiles- they're linear, they dont' do any special damage or effect, but they CAN open up the opponent to attacks.
For our Heat Gauge character, let's add Machine: Orbit. This will give us specials with great amount of reach and projectile ability, at the cost of having to manage a set number of "orbits". We can't overuse the projectiles, or we won't have any to defend ourself if the enemy gets through. By using up the Heat Gauge, the orbits catch fire and deal the fire special, knocking back an enemy very far and high (although they're invulnerable during that.)
Layer Three: This Hand Of MineLastly, we choose what specials we have and how our SP gauge works. Layer 3 options are dependant on Layer 2- someone with slow, homing, electric projectiles can't suddenly pull a poison attack. They're varied enough as well as having some universal specials, the umbrella is always quite wide for any choice in Layer 2. Such as:
Our fast, slashy, charge-it-up character could use some boosts... Why not choose the Melee and Boost specials? This gives us a normal 0-100 gauge for specials, and gives us a mix of up-close specials as well as the ability to boost ourselves temporarily.
On our character, we get two skills at 50 and one at 100. At 50, we can either instantly charge our Mode 2 gauge to maximum, or dash forward and slice the foe into ribbons. At 100, we can do a dash that knocks the enemy high into the air, where we charge up to max with Mode 2 before delivering a devastating aerial assault.
Let's make our good-overall striker into something more interesting, shall we? By taking Eldritch Visions: Tension, we can get other-worldly attacks on a Tension Gauge (0,1,2, or 3.)
Not only are we now themed, we also get some good specials. At Tension 1, we have three skills, at Tension 2, we have two, and Tension 3 gives us one skill.
Tension 1:
Apparition- A poof of black smoke, and you're now on the other side of the enemy at the same distance you were before.
Release A- A "grab" that breaks guards along the entire ground-level using a tentacle. Drags the enemy close then slams them into the ground repeatedly.
Release B- Your mouth unhinges, firing a black inky blob with a single eye. It's somewhat slow and dosen't home in, but if it hits, the opponent takes considerable damage and becomes confused (reverse controls).
Tension 2:
Apparition Reaction- You'll go "poof" and appear behind the enemy next time they successfully hit you. Works once.
False Apparition: A shadow of you appears where you would if you were to use Apparition and mirrors your attacks for a short while- it's attacks also hit the enemy.
Tension 3:
Real Apparition- An instant-kill grab. Not super-hard to dodge, but if it connects, a shadow appears the same way as False Apparition and does a powerful combo with you.
Let's really live up to our Mechanical form and use Mechanical: Stage Traps. We use a 1-100 SP gauge for this, but it's split differently than the first time:
at 25 SP, we have two specials
at 50 SP, we have two specials
at 100 SP, we have a special and an instant kill.
25SP: Ground Gear: Creates a moderately fast spinning gear that moves back and forth a few times across the ground. Attacking it changes it's direction, getting hit by it does a small amount of damage and flings the victim in the air.
25SP: Exhaust: Creates a cloud of exhaust that does a small amount of damage to anyone who hits it as well as knocking them away. Reduces the Heat Gauge somewhat.
50SP: Grind Gear: Launches three Ground Gears at variable speeds. They dissapear faster, but do more damage and more hits.
50SP: Grind Blade: A grab attack that, when successful, spins the Orbits around for a combo that deals a good amount of damage as well as many hits. Leaves the spinning blade for a little while after the combo, leaving you vulnerable for a short time but leaving a big wheel of death on the stage.
100SP: Mechanical Circus: Creates 5 Ground Gears at variable speeds that don't disappear unless damaged, they also won't hit you. At the same time, launches the orbits in random arcs across the air. Invulnerable for a small amount of time while the orbits come back.
100SP Instant Kill: Missile Silo: Places a marker a certain distance ahead- after a random amount of time, the ground will open and a missile will launch upwards. If the enemy is hit by it, it is an instant kill.
An idea I had- you could build characters way different from mine with the same bases, or have similar skills with very different bases, and custom-build your own fighter to fit your style.