Hi Sally,
I am very fond of Cubistry. Two good word games I have are Jumbline 2 and Cryptogram Puzzles. One game I liked but blew off because it really drained my battery fast, Buttons and Sissors(Pro). I check the apps site every day to see what they are offering freebie. I rarely buy any of them. A super program (not a game), if you like Astronomy, is Distant Suns. I had that program on my Amiga way, way back when. It is excellent and worth paying for. I've been waiting for the Pop Cap people to make an app for BookWorm that is compatible with the Fire, but it doesn't look like that is going to happen.
You can go out to the web with your Silk Browser. If you have favorite websites, bookmark them. Check to see if the app store has apps (like many entertainment and news channels) which make it even easier to get to where you want to be. There are some search engine apps; I use Duck Duck Go Go . And no, I have no idea why they call themselves that.
I use a cleaner program to clean up temp files and such, but once in a while I go into the "More" menu click on Silk Browser and do a clean up from that submenu. It helps to free up space and can speed things up a little. If you don't have a anti-virus program on your Kindle, I recommend getting one.
If you want an app that isn't in the Kindle app store, it can be done, but it can be a tricky procedure to get Kindle to recognize it and not cause problems.
I hope this info is helpful to you.
Margie