BTL is an extremely-addictive way to get simsense feeds in Shadowrun. By boosting the output of the ASIST feed to illegal levels and modifying one's simsense player to handle the increase, one can have pleasurable experiences beyond what is attainable by mere interaction with others. Like the street drugs of the twentieth century, an entire subculture has developed to cater to these individuals- dealers lurk in strange places, occasionally selling new chips to their customers, who range from street gangs to high-level government officials.

Three major classifications of BTL chips exist. The most common is the mixture of BTL impulses with traditional simsense methods, creating a highly... evocative experience. The second is called a trackloop, as it plays a single emotion or sensory experience constantly for the user. The RAS override is usually cut out, allowing the user to interact with the real world while still chipping. The last is called the personafix, and is one of the more potentially dangerous due to its capacity to alter a person's base personality reactions.

As a general rule, BTL chips are designed to burn themselves out after one use as a way to keep the dealer in business. If the user knows a microtronics worker, though, the chip can be jiggled to keep it functional all the time.

Although they do not harbor any of the innate physiological-altering effects of a number of hard drugs, BTL chips are just as dangerous to their user as a good dose of crack cocaine can be- there's always the chance that one might get a chip with too high an ASIST output that could trigger a fatal feedback loop...