Fragger Level 29 is my favourite level and is the hardest to figure out. However once you have figured it out its rather easy to accomplish many times over due to the number of grenades you are allocated on normal difficulty.
Step 1: Loop a grenade down the first drain pipe attached to the front of the house so it rolls down and into the tunnel under the house. It should nestle under the fragger man and blow him up leaving the box of TNT on the ground.
Step 2: Loop a grenade into the chimney at the front of the house so it lands on the edge of the platform inside the house and blows up the guy on the right handside who has a bomb on his head.
Step 3: The next step clears a lot of the obstacles in completing the level. Throw another grenade down the first drain pipe of the house once more so it then nestles below the TNT.
The TNT will explode along with the other box of TNT over on the right. This will cause a large blast that will take out the guy on bottom floor on the right. The explosion will also crack the ledge that was blocking the entrance from the second drain pipe of the house and take out the ledge that was holding the bomb.
Step 4: Loop a grenade so it bounces lightly on to the second part of the roof of the house. It should have enough momentum to roll down the side of the house and into the second drain pipe.
When the grenade lands at the bottom of the house it should propel the bomb up to the top floor of the house which will explode and take out the last two fragger men. That's level 29 complete!