public ViewModel() { VisibleBlocks.Add(new ObservableCollection <Block>()); VisibleBlocks.Add(new ObservableCollection <Block>()); VisibleBlocks.Add(new ObservableCollection <Block>()); VisibleBlocks.Add(new ObservableCollection <Block>()); for (int x = 0; x < 4; x++) { for (int y = 0; y < 4; y++) { VisibleBlocks[x].Add(new Block()); } Blocks.AddRange(VisibleBlocks[x]); } RandomBlock(); RandomBlock(); }