Abstract: Systems and methods include a device and an algorithm for measuring adherence to various activity goals (e.g., time-based goals) and collecting ad-hoc game metrics using accelerometers or other sensors. Some embodiments can provide reduced computational, memory, or communications costs over conventional algorithms. In one embodiment, the resulting reduced battery usage can enable a device that is long-lasting, without the need for frequent recharging. This reduction, in turn, can enable the device to be sealed with limited or no external access. Another embodiment can include or interact with social networks and other online data sources to improve activity recognition.