Yes you can, on the plane just go to Settings - and turn Airplane Mode on. Some games do need the Internet to play but there are a lot that don't. You can just test these at home by turning off your wifi and/or 3G and see if they still play. If you have a 3G/4G iPad and have a sim inserted from home be aware of Cellular and Roaming data charges, it's a good idea to turn these off when abroad as these charges can be huge, go to Settings - Cellular Data and turn both of these off here. If you have a need for 3G while abroad, it is much cheaper to buy a local sim where you will be going. Hope this helps.
The IPad Forum is a community of members from all walks of life and from all over the world coming together to share our experiences and to help each other learn about this wonderful piece of technology the Ipad. There is a wealth of information already here in the many threads we have so doing some searches will answer most of the questions you have. If then you cannot find the answer you are seeking then by all means post your question. There are many friendly and informed members here only too willing to help you.