Mahjong by Microsoft, Minesweeper, Jigsaw, and Ultimate Word Games all have the option to zoom in & out of your game while playing.
In Mahjong by Microsoft and Minesweeper if you have a touch screen device, you only need to pinch on the screen to zoom, like in most other applications. You can also use the scroll wheel on your mouse to zoom in and out.
In Jigsaw, you can use touch controls as well to zoom, or click on the magnifying glasses in the sidebar while working on your puzzle.
In Ultimate Word Games, you can zoom in Wordament and Crosswords. In Wordament, you can zoom with touch controls or the scroll wheel on your mouse. In Crosswords, click the zoom button to zoom in. Then use the right and bottom scroll bars to move the puzzle around. To zoom out, click the zoom button 3 times. You can also click on the Expand the Grid button in the upper right-hand corner to increase the size of the puzzle.