Hi Bob95742, welcome to CruiseReviews! I am so happy to hear you're going to join the world of the cruise addicts
There are a couple other things that are included, like the afternoon tea, and most all of the games including basketball, ping-pong, but not video games. Some ships have putt-putt golf, some have driving range simulators, all have pools and hot tubs. Most of Carnival's ships have water slides, and the Movies Under the Stars (which is also free).
You can see between Susan and Dave there is a huge variation on what can be spent on board. I usually purchase liquor on board and a carton of cigarettes to bring back. They have perfumes that are duty free, as well as jewelry, clothing, and accessories, so you will save some money as opposed to purchasing them in the states.
Tips can be prepaid or added to your shipboard account. You can either use cash, debit card, or credit card for your onboard account. They will issue you a room key that is also your credit card while on board. If you use a debit card, they will place a hold on your account for a certain amount of money. If you pay cash, they require a certain amount before you leave. If you spend your cash deposit, you can go to the purser's desk and put more cash on the account. The easiest is just to use a credit card.
Cruising is the most affordable vacation one can find, and absolutely the best!