Differences between SST and SSTU

Graphical Changes

 * The characters are notably bigger and more detailed compared to SST's. They also do not lose quality because they were shrink'd down manually (this happened with K. Falcan, Draco, Pika/Scrub, Tod and Jiglypof in SST).


 * The knockback smoke has transparency effects and disappear faster compared to SST's. They also appear more frequently when a character is launched.
 * Some projectiles create epic effects when it hits a wall/an opponent (Peecmen's Down B and Looge's Neutral B for example).


 * The game's HUD has also been changed, and it's more like the official Smash games (position-wise). Its shape is also different, being a circle instead of a square. It's also worth noticing that it does not show the characters' Series Logo unlike SST 4.0's HUD.


 * The game's resolution is way bigger, same goes to the characters and stages.

Gameplay Changes
The amount of gameplay changes in SSTU are huge, mostly because it uses a completely different plaforming engine. The new engine is way more complex compared to SST's platforming engine, but it has a good amount of advantages. One of them is being able to do a wind effect, something that wasn't possible with SST's platforming engine.
 * The knockback system is completely different; it does not change the opponent's current direction and might send them backwards if they aren't facing you. And gravity is still applied to it, which explains why the opponents "bounce" when they get hit by a move with a lot of hitstun. When you hit an opponent that's falling with a move that sends them upward, it's not actually going to send them up most of the time. The knockback speed is also always the same.
 * Instead of just seeing how far X player is far away from the screen (SST), it has actual blastzones. This change really helps playing on big stages.
 * Movement was also really changed as well, There's actual acceleration and deceleration.
 * There is no more Zig-Zag-Boxing.
 * Some characters have different weights. Eegmeen for example, is a heavyweight, while Pecho is a lightweight.
 * As you might have seen from SSTU's main page, all characters have 6 attacks instead of 2.