Though it is in Japanese, it's challenging to get the game going but can be done.
Instructions on how to play:
1. Go to http://www.jra-jwc.jp/vol1/. 2. Wait for the big flash file to load. 3. Click Skip. 4. Click the button that follows your mouse. 5. Click Bet at the bottom. 6. Click the button that follows your mouse again. 7. Select any of the three options. It seems to be different betting modes. 8. Select a horse to bet on, the click the pink button. 9. Eventually there will be 2 buttons to choose from. Click the left one to go back to step 6 and buy more tickets. Or the right one to start the game.
Office chair horse is off to a flying start.
Not sure how interactive the game actually is, but it looks hilarious.