memory*, more appropriate difficulty level
fixed a typo

replaced "Wahington D.C." by "Washington D.C."
fixed a typo

Replaced "an look for gold nuggets" by "and look for gold nuggets"
fixed a typo

Replaced "There is a close gate" by "There is a closed gate"
fixed typo

Replaced "your have to catch" by "you have to catch"
fixed typo

Replaced "Open or close the the ballast tank." by
"Open or close the ballast tank."
fixed typo

Replaced "When done you are suggested an exercice" by
"When done you are suggested an exercise"
fixed a typo in mouse gestures
fixed confusion around translator context.

It is now requested to the translator to remove the USA| and ASIA| context
Now the translation appears properly in the user interface without the
context.