A leverless controller is supposed to eliminate sluggish joystick movements. Sometimes, it has only buttons or a mixture of buttons and keys.
Order your Kombox Impact preassembled with Sanwa buttons or in DIY format, and there is a joystick edition too.
The Atachon BEATdown is an all-key controller that looks like a cassette tape, and it has extra keys for the left pinky & right thumb.
The Haute42 M16 can also be a WASD controller. As for the M13 edition, it has three less buttons than the M16.
Choose one of more than a dozen all-button layouts when ordering the slim and mini SL-X controller from BattleMonkey.
The Punk Workshop Leverless U provides a plethora of features, such as slimness, many layouts, different colors, and custom art.
The SGF Faust is a mini stickless controller with LED plus a TRS jack for external input sources like foot pedals.
The Glyph is a modular all-button controller that is available in layouts for games from Smash to Street Fighter.
The Neobox Core0 is a slim acrylic all-button controller that is here in order to serve your need for RGB LEDs.