Here's a new installment in Anita Sarkeesian's Kickstarter-funded, misogynist-enraging, must-watch "Tropes vs Women in Video Games" series: Ms Male Character: a closely annotated, fascinating 25 minutes on the practice of producing a "female" version of video-games by feminizing the lead characters.
The Adult Swim game Giant Boulder of Death takes the trope to ridiculous extremes by gendering a pink boulder with a giant pink bow before she's stuffed in the refrigerator to motivate the blue boulder to seek revenge.
Now the interesting thing is that these gendered signifiers are really quite arbitrary and abstract. There's nothing about a bow in and of itself that is intrinsically or essentially feminine; it's just a piece of colored fabric, after all. But our society currently assigns a very specific, socially constructed and strictly enforced meaning to that piece of fabric. It's a symbol that conveys the concept of female (and invokes the idea of girlhood.)
The indie game Rogue Legacy has an interesting system whereby you can be randomly assigned the choice of either male or female heirs to play on each run. The characters are essentially identical both mechanically and aesthetically (except for a very minor difference in their breast plate styles). So far so good, but all the female heirs also have a strangely conspicuous and completely unnecessary lavender colored bow on top of their armour. This is a classic example of put a bow on it!
The colour-coding of characters is another frequently used visual element to signify gender. Typically the dominant color used in the design of the female variant is bright pink (although sometimes a purple or pastel palette may be used).
In the 1985 NES classic Ice Climber, player 1 controls Popo who wears a blue parka. If you have a 2nd player they can control Nana who wears a pink parka.
