As many suspected, Nintendo has swapped out its Club Nintendo game offer mid-month, switching Electroplankton: Rec-Rec for Starship Defense, a sort of tower defense thing by Pixeljunk developer Q-Games.
The Club Nintendo download is only available for 3DS owners, for 150 coins.
Buy: Nintendo 3DS XL Red or Blue, Nintendo 3DSFind: Nintendo DS/3DS release dates, discounts, & moreSee also: Previous Club Nintendo rewards