Update: I can now confirm that if you want to play DS games on a 3DS in the best possible quality, you should definitely get a Nintendo 3DS XL and play DS games in ‘native’ mode (see below). This will negate all the scaling issues I describe below and the game will be playing it as sharp as it’s meant to be, and at roughly the same size as it was on one of the original DS models.

The short version

The Nintendo 3DS is perfectly compatible with DS games, but due to the differing screen resolutions and pixel density, DS games can be played in one of two ways:

• Scaled up: the sharpness of the visuals may appear to be reduced, but the game is not distorted like Game Boy games were on the GBA
• Native resolution: the game is as sharp as it’s meant to be but ends up looking smaller than if you played it on an original Nintendo DS and a lot smaller than a DSi XL. Get a DS game to load in this mode by holding down start+select as you load the DS game and keep them held down until the game loads.

Screenshots coming soon.

The long version

Nintendo World Report reported yesterday about how DS games look on the Nintendo 3DS. They point out that when playing a DS game on a 3DS you have two options: the 3DS can ‘scale up’ the DS game, or you can play it at its ‘native resolution’. However scaled up the games look blurry, and at native resolution the games look small. Why? Why can’t it just be the right size and look sharp? Nintendo managed it with the Game Boy Advance and Game Boy games right? In fact, NWR compare what is happening on the 3DS with what happened with the GBA. In doing so, they get it completely wrong:

Games look just a little off in the same manner that Game Boy games looked weird stretched out on the Game Boy Advance.

I don’t know if the author ever had a Game Boy Advance, but here’s a side-by-side comparison of a Game Boy game running on a GBA SP with and without stretching (activated by pressing one of the shoulder buttons):

Stretched on the left, unstretched on the right

Stretched looks horrible (and is not what is happening on the 3DS), but un-stretched looks fine right? Doesn’t appear to be too small. So why can’t this happen on the 3DS? This blog post looks at what’s going on from a hardware point of view, to try and correct the misreporting and confusion going on.

The GBA and GB appear to have the same pixel density, which means the same number of pixels fit into the same amount of physical space. This means that a Game Boy game played on a GBA (without stretching) is identical in size (e.g. if you measured it with a ruler) to the same game played on a real Game Boy. As a result, most people played Game Boy games un-stretched on a GBA because it was just the same as playing it on a real Game Boy.

Pixel density allows for bigger screens without changing screen resolution; just make the pixels bigger. That’s why the DS and DSi XL have different sized screens but retain backwards compatibility; they have the same screen resolution but different pixel densities. Likewise, you can fit more pixels into the same space with a higher pixel density which makes images look clearer and sharper.

Now what about the 3DS? For starters, look at this physical comparison of the DS and 3DS screens:

See that tiny dark border? That’s how much larger the 3DS screen is. So why can’t DS games just look normal on the 3DS? The screen sizes are the same, it should be possible just like it was with the GBA right?

Wrong, and the answer is pixel density. The GBA and GB had the same pixel density, so games looked identical. But the 3DS has physically smaller pixels than the DS. The 3DS screens are 400×240 (upper) and 320×240 (lower) respectively. Ignoring the black bars on either side of the upper screen (necessary to make the game line up, as the DS had identical sized screens) we essentially have 320×240 on both screens. But the DS had a screen resolution of 256×192. Here’s a comparison of the DS and 3DS screens as if they had identical pixel densities:

So, the DS has a smaller screen resolution and bigger pixels, which is why there is no ideal solution; either the image is physically smaller, or the image has to be ‘scaled up’ to run at a higher resolution at the same physical size it ran at on the DS. The result of this is that some games can look blurry, particularly ones using pixel-perfect artwork like Pokémon. However it does have the advantage of providing a kind of poor mans anti-aliasing, which means jagged lines are reduced.

Note that the aspect ratios are identical however, which completely debunks Nintendo World Report, as it means games are not distorted in any way other than that they have been ‘scaled up’ to run at 320×240.

I hope that’s explained the situation sufficiently; it’s quite difficult to describe screens when you are talking about both image size and physical size!