Hmmm... ok... did this a lot back in school. There were so many games, and variations because of the rules and such. Anyway, hope this will keep you fruitfully occupied for some time:

-Play 3 dimensional X and 0, or tic-tac-toe. You can do this either on paper (easy mode) or mentally (gets easy with practice mode). Draw three stacks of the 3x3 grid, and anyone who fills in the grid in a line wins. If you are playing it orally, use a co-ordinate system. So, (1,1,1) puts in an X in one corner of the cube, and (3,3,3) puts it in the other corner. Protip: Instead of trying to visualise it, look at it using the numbers, so anyone who gets say a (1,2,1) a (2,2,2) and a (3,2,3) wins.

-Play word games. Either go on a memory string, start with the last letter. Or, exhaust all the words in a particular subject with the letter A, say all the animals or places that start with A. When anyone get's stuck, give that fellow a "D" for Donkey, and proceed to B. You can also do an alphabet memory string, going. Animals, Birds and Places were the most common items we chose.

-I dont know how the bus tickets are in your area. In Mumbai, there are two sets of numbers, one a three digit or a two digit number, and another a 6 digit number. Use the numerals in the 6 digit number. Add, subtract, multiply or divide them to form the 3 digit number. There are many ways to do this, so you can last a long time on just one ticket (yeah we were really bored too). First see in how many ways you can arrive at the number. There are variations like disallowing certain operations, allowing any two of the numerals to be clubbed together, or allowing players to not use all of the six digits. Then, exchange the 6 digit numbers, and use it with the 3 digits of the other ticket. After all those options run out, reverse the 3 digit numbers then have a go again.

-Use a notebook for this. Draw a small home on one corner. Then write in numbers all over the page in any position, or in an organised grid. Use numbers from 1 to 16, or 20 or 25. Then, one player has to start drawing a line from the "home" to any of the numbers that the other player calls out. The aim of the player drawing the line is to navigate to all the called out numbers in the grid, then go back home. The aim of the player calling out the number is to make the player drawing out the line to cross his own line. The player drawing out the line is not allowed to lift the pen from the paper, and if his line intersects, he loses.

-Tear out a few sheets of paper from a book. Distribute sheets to everyone who are playing (at least 4). Now write a question along the top of the page, fold the part over, and pass on the sheet. The next person, writes an answer, writes out another question, folds the sheet over, and passes the page to the next person. Once the sheets are filled, open them out and read out the questions and answers. This is a hilarious passtime.

-Draw a ludo grid on the table using chalk, then use pieces of chalk, or seeds to play. Bring along dice though.