What could possibly go wrong?

Well, a lot.

Considering the huge potential that games have for international expansion and that almost 90% of the world does not speak English, professional localization is a very wise investment that pays off quickly.

Unfortunately, translation buyers often are not aware of just how bad poorly localized games can look. Worldwide users do, and this has a huge effect on usability, on the perceived value of the game, and on the company's brand image.

These are just some examples of issues that are very commonly found in localized games:

“I am a superheroe, yet I speaks in unrevisioned english with pleny of typos and pooor, amateurs writing.”
Games that are not translated and reviewed by professional linguists are poorly written and contain bad, embarrassing translations that scare buyers off.
“Thou art thy mother's glass and she in thee.”
It is quite common to find translated games in which the tone is not appropriate for the age or gender of target audience. The result is unusable.
-How will we get past the wall?
-Um, I meant “Watch” (me).
Often the same string must be translated differently depending on the context. If your team is not expert, the translations will often be totally wrong. This is particularly important when translating games, where strings are often short and much information is visual.
Translations tend to be longer and they may not fit in the space available if not done carefully. Help your translation team by designing the interface to allow longer translations or provide a system to reposition text for each language.
Texto en 중국어 Sprachen?
Strings in English or mixed languages often make it into localized games. Your users would not like it at all.
Conglaturation! A winner is you!
No, using machine translation or a native colleague for one missing string is not a good idea. Sometimes one wrong word can make a big difference.
Ask Jim (wasn't his name John?) to use his badge (you mean his card, right?) to open the boot (trunk?) and take the sword (is that the same weapon as the dagger?).
Using inconsistent translations for the same source term can be really confusing and frustrating for players.
"Oops! Error 180 (OXB!)"
Some items or features may not work if they have not been localized or tested properly.