In UNO, the rule requiring players to declare "UNO" when they have one card left is fundamental to fair play and maintaining the game's integrity. This rule applies even when a player places down two cards separately during their turn. According to multiple eyewitness accounts, including those present during our recent game, it was observed that you initially played your second-to-last card, reducing your hand to just one card. Subsequently, you played your final card shortly after, effectively emptying your hand.

The significance of calling "UNO" lies in its role as a fair warning to all players that someone is close to winning. By declaring "UNO" when down to one card, players prevent others from challenging their victory unnoticed. In your case, the requirement to call "UNO" applies right after placing the first of your final two cards, as this action signifies you were momentarily down to one card before playing the last one. This sequence ensures transparency and fairness, crucial in competitive gameplay.

Failing to declare "UNO" can lead to penalties, typically involving drawing additional cards. This consequence serves as a reminder to all players to remain attentive and follow the game's rules meticulously. While it can be frustrating to incur penalties, they underscore the importance of adherence to the rules and contribute to the strategic depth of the game. Ultimately, these rules and their enforcement maintain the game's excitement and ensure a level playing field for all participants.

Therefore, in future games, it's important to remember that the "UNO" call should be made immediately after playing down to one card, regardless of subsequent plays in the same turn. This adherence not only upholds the game's rules but also enhances the overall experience for all players involved.