Why is this brilliant?

I know its an alright move, but I'm not quite understanding why it is a brilliant move

Vote Chess for Beginners 1200 ELO) - Your Move! Rules in Comments.

Felt there was a mate during the game, but couldn't find it. Can you find this mate in 6?

I almost premoved it, but then I just chose the wrong move at one point.

Rook for a bishop nuance

To take or not to take. it’s early in the game, also Notice that the rook isn’t very active (especially compared to minor pieces). And I’m left with a bad bishop after the trade off (and underdeveloped) b/c atm blacks pawns at on light squares. And I still need to castle In the event of an end game, which is likely because we are evenly matched I think the trade is better. But atm I don’t think the material advantage helps me because our position and stage in game.

Average 1200 elo game

In this position I had M10 on the board but I blundered a draw. What's worse is I had a feeling there was a mate but I had no idea how to execute it.

Can’t win

I just don’t get it…

Forget checkmate. Black to play and win a queen by force.

Just got this in an OTB tourney. Knew there was a checkmate here but saw another tactic I couldn't pass up.

Can you guys wish me luck?

Everywhere a knight can move within two moves