A random event happens every 2 or 3 days (I'm not really sure about how long an event will take to happen, leave a comment down below!). The event board will be a button that you click to access the page. Once the page is accessed, it will show any events that is happening. events stack up to 3, and you click the certain event to do it! The event board will notify you of events with visuals such as exclamation marks on the event board button.
An event I had in mind was an Alien Event! This has a 5% chance to happen, and when it does, aliens abduct your current cookies in the bank. You will have to start the event to get the cookies back! Once started, you will be fighting UFOs in a space shooting minigame way. If you lose the event, 5 shipments will be taken away from you. After winning the event, a notification will pop up on the screen, asking if you want to continue, to conquer the aliens shipments. If you choose to continue, you fight the mothership, which is a quite difficult boss.
Another event I was thinking of was a Cat Fight. This has a 20% chance to happen, and when it does, you enter a battle with the current cats you own right now. Each cat you own have different abilities. The Fight would be similar to that of a pokemon battle. When you win the Cat Fight, you move on to the next stage, up to 5 stages. If the Cat fight is won, you have to wait for the event to happen again to move onto the next stage. So in total, you will have to had to play this event a minimum of 5 times. And dont worry if you lose, your stage checkpoints and saves, so when the event happens again, you will start on the same stage. Each victory of a stage will result in getting an award that comes as an upgrade. The last stage gives you an epic upgrade. (P.S, the cat fight is replayable but instead of getting upgrades as a reward, you get cookies.)
Upgrade#1: Kitten Steroids (+1% cps per Kitten owned.) Upgrade#2: Nine Lives (+2% cps per rank of milk.) Upgrade#3: Sharpened Claws (+0.1% cps per milk percentage level.) Upgrade#4: High Quality Tuna (Adds a golden cookie effect called Fresh From The Utters: Your cps is multiplied by 100 per milk rank. Lasts 7 seconds.) Upgrade#5: Lion Kitten (You gain more cps the more milk you have.)
There will be more events added in, and will take up the other percentages. I also have other ideas that will have to with Cat Battles, such as it not only happening as an event, but as another instance!