8Bitdo M30 Bluetooth Gamepad

 A row of four LEDs on the bottom edge of the controller show the connection status and current mode

A USB-C port sits on the top edge between the shoulder buttons, along with a small Pairing button. The M30 includes a USB-A-to-USB-C cable for charging the controller. As a six-button Sega-style controller, the M30 makes a few control tweaks when working with the Nintendo Switch, or when playing any game that expects four face buttons and two pairs of shoulder buttons.

To start, the A/B and X/Y button pairs on the controller are swapped when connected to a Switch the B button works as the A button, the A button works as the B button, and so on. This can be confusing if you look closely at the button labels, but it's natural in terms of their arrangement; the A, B, X, and Y buttons are all arranged in a diamond using the Sega (and Xbox) placement system, which is the reverse from Nintendo button placement. 

Direction pad

Regardless of the M30's specific inspiration, the controller has the same basic control layout of both the six-button Genesis and Saturn controllers. The direction pad is a large disc with a prominent plus shape and triangular notches for the diagonal directions, and the face buttons are laid out in two rows. The lower A, B, and C buttons are large, black, and concave, while the upper X, Y, and Z buttons are smaller, light gray, and convex.

Neither set of buttons is nearly as large or flat as the face buttons on the Hori Fight Commander. For a specifically Saturn concession, the top edge of the controller holds L and R shoulder buttons (which the Mega Drive/Genesis lacked). A small, blue, rectangular Start button sits in the center of the M30, with three small, black, circular buttons below it: Star (Capture, when used with the Switch), Minus (Select), and Heart (Home, on the Switch).

Left four face buttons

If you think of the left four face buttons as just like the face buttons on the Joy-Cons and SNES controller, and ignore the labels on the buttons themselves, you'll be fine. The C and Z buttons, located to the upper right of the A, B, X, and Y buttons map to the L1 and L1 triggers when connected to the Switch. The left and right triggers, meanwhile, map to L2 and R2. By default, the direction pad doesn't correspond to the direction buttons on the Joy-Cons. Instead, it acts like the left analog stick.

This isn't a problem for most retro games like the Mega Man series or anything on Nintendo Switch Online, but it can make certain games inoperable. For example, I couldn't play Tetris 99 because moving the blocks is exclusively done through the direction buttons rather than the analog stick. You can remap the direction pad to work as the direction buttons or the right analog stick, but it's an obscure function that isn't clearly explained in the controller's documentation.

Press and hold the Select button and Up, Left, or Right for three seconds until the LEDs blink

Holding Up makes the direction pad work as direction buttons, holding Left makes the pad work as the left analog stick, and holding Right makes the pad work as the right analog stick. You're still limited to only one of those directional inputs at a time, but it's a useful function if a game isn't working quite the way you want it to.

Like 8Bitdo's other Bluetooth gamepads, the M30 can work with several different devices, depending on what mode you set it to when you turn it on by holding the Start button and one of the face buttons. The controller can function as an XInput device for working with PCs, a DirectInput device for working with Android devices, a Mac-compatible gamepad, or even a Nintendo Switch controller. It's a lot of flexibility and useful if you have both a Nintendo Switch and a computer filled with classic games. 

The only bit of inconvenience here is the lack of an explanation sticker on the back

The SN30 Pro, N30 Pro 2, and even original SN30 all have small stickers on the back that show the button combination you need to press for each mode. Until you memorize the modes you want to use (Start and Y for Switch, Start and X for PC, and so on), you need to check the instructions to connect the gamepad to anything. The 8Bitdo M30 is a Bluetooth gamepad designed for a very specific type of gamer: the nostalgic Sega fan.

It looks and feels like a wireless version of the Sega Genesis/Mega Drive's six-button controller, with a few minor additions like shoulder and Capture/Minus/Home buttons. Without the analog sticks that most modern video games require, it's almost exclusively for 2D classics, though its large, circular direction pad and six-button layout make it excellent for many fighting games as well.