The WonderSwan is a weirdly specific blip in time. Nothing on it is as time-sensitive as the MobileWonderGate, however.
Released as early as July 14 of 2000, the handheld was looking to breach the new world of wireless connectivity. An add-on would clip to your handheld, as well as a mobile phone, then communicate with a special cartridge to browse the net.
A few games received added online features and even a few downloadables were announced, but the service was sunset only one year later without any games ever seeing the light of day.