Movement
Double Dragon has your standard fighting game walking and jumping, but adds double jumps and a fairly unique take on dashes to the mix.
Jumps
Jumping works like any other fighting game. Input 7 to jump backwards, 8 to jump upward (neutral jump), and 9 to jump forward. All jumping buttons must be blocked high (holding 4). All jumps have just 3 frames of startup.
In Double Dragon, you can act after any air normal. This means you can stick out a jumping button twice, or attack and then double jump, and so on. You can air block when not in the middle of an air attack by holding 1 or 4. Air blocking works on everything besides air throws.
The landing recovery from jumps is typically 8 frames (16 for Abobo!) but is reduced to 1 frame by holding any button, attacking or jumping. You can block during his time as well, so you can say this game has trip guard.
Dashes
Dashes or "hops" are performed with 66 for forward dash and 44 for backwards dash. During a dash, you can press any button to get a jumping normal, input 7/8/9 to double jump, or hold 1/4 to air block.
Dash normals vary from jump normals in that they're mostly mids. All 66Bs still have to be blocked high, and there are other exceptions detailed on the character pages.
Because of this, and the tendency to land closer after a jumping normal - especially on crossup - there's still reasons to jump instead of dash.
Each character's dashes have the same landing recovery as their jump. Oddly, you can't dash if you're holding down any button. This might come into play when trying to dash after landing from a jump.
Offense
Counter Hits
If hit during the startup of any move, you'll see COUNTER pop up. In this game, counterhits deal ~1.25x damage and also cause extra stun. They don't change hitstun, but there are counterhit-exclusive stun combos.
Stun
Stun, also referred to as dizzy, comes in two forms. If you hit an opponent enough times, they'll be stunned. You can tell by the stars or sparkles spinning around their head.
If you stun someone with an attack that knocks down, they'll be stunned while knocked down, allowing you to pursuit. Pursuits are performed with 2 and any button, and Abobo's 632XX super can also hit.
You generally want to stun someone and leave them standing, since you can follow up with whatever you want if you're fast enough. You can mash out of stun, which is why you often see people using knockdown-stun time to set up an ambiguous crossup.
Charge Guage (Super Moves)
Your health bar shows lost health in red and remaining health in yellow, and the Charge Guage in blue. Once your remaining health is fully blue, your health flashes and CHARGE appears over your name.
During this time, your character can perform a Super Move by inputting a special move, but pressing any 2 buttons. Needless to say, the more damage you have taken, the less it takes to fill up your Charge Gauge.
You can fill up your super meter by dealing damage, or even just having attacks blocked. Damage and stun are both increased in the Charge state.
To avoid confusion with "charge" inputs such as [4]6A, we'll just call Charge "Super" in all contexts. You can consider having full Super as similar to Max Mode in early KOF games.
Hitstun stacking
The hitstun of heavy attacks (C or D) is passed on the successive hits in a combo. This results in combos that otherwise wouldn't connect, including infinite strings. It was thought you needed 2 heavy hits, but you can also get increased hitstun with D>B normals.
One easy example to illustrate this is Marian's infinite: j.C (n.5C 5A 66B)...[1]
Where it gets complicated is how too many heavy attacks will force knockdown. Even if it wouldn't normally, any combo of C into D or vice versa will knock down, as will 3 C normals, or C>C>B>C. It seems the hitstun has to fall off enough to avoid this.
For the sake of clarity, this wiki uses attack levels 1, 2, 3, 4 for the histun/hit effects typical of A, B, C, D normals. You can tell what level an attack is hitting at by the rounded hit "spark" that appears.
Defense
Blocking
Characters can block on the ground with 1 for low attacks, and 4 for high attacks. Attacks are referred to as mid if they can blocked either way. You can also block in the air with 1/4/7. This works against any attack, but everyone except Cheng-Fu and Eddie have air throws. Chip damage exists on specials, and on normal moves only against air blocking. You can avoid being juggled with normals after air blocking by double jumping - you always get it back after air blocking.
Throws
Throws in this game are proximity throws, which means they only happen if opponents are in range. Each character has throws on the ground with 4/6 B/C/D, but air throws vary (everyone has one on D). You can air throw with any direction but 2/5/8.
Command throws are also proximity-based, and can be comboed into as well as negative edged. There isn't any throw protection on wakeup, but there is on hit (normal throws) and block (all throws).
