Paper Mario World is a really good-looking fan game which you control Super Mario with a hammer in his hand as a weapon! (P. S. The game may run slower if you haven't a powerful computer. In this case just change the quality by clicking the button on the top right corner of the screen).
Use your arrow keys to jump and run and press space to use your hammer to crunch the enemies. Use your hammer to crush enemies or do it in the traditional way, jump on them. If you defeated all the enemies you will be rewarded with a password for an extra mode. Use the ARROW KEYS to move around, press SPACEBAR to use hammer. Have fun!