Here are some ideas to make a game of chases more fun.  Some you may already know...

 

 Chain Tag - One person is IT but, anyone who is caught has to link arms and join in being IT.  If the chain is broken when someone is caught, it doesn't count.

Stuck in the Mud - if you are caught, you have to freeze.  Untagged players can be allowed to unfreeze anyone who is "stuck in the mud".  Normally, the game is won if the person who is IT manages to freeze everyone.

Shadow Tag - the person who is IT needs to tag someone by standing on their shadow.  Works well in the late afternoon when shadows are longer.

Line Tag - you will need lines drawn on the ground for this - so a playground with hopscotch lines or a tennis court or even lines in the paving.  You can only run or walk on the lines.  You're out if you step of the line.  If you are tagged, you sit down and only the person who is IT can move past you.

Zombie/Ghost Tag - the person who is IT has to chase everyone but acting like a zombie/ghost - arms outstretched, groaning.  Everyone who is touched becomes a zombie/ghost.

Hide and Seek Tag - like hide and seek, except that, when found, the hiders can run back to the starting point and be "safe".  If they are tagged before reaching the starting point, they join the seeker.  Last person to the tree or to be tagged will be the seeker in the next game.