The first thing you might notice about the TI-99/4A version of Espial is its weird cartridge shape. This is due to the fact that it plugs into the system's expansion port (where the Speech Synthesizer plugs into) instead of the normal cartridge port. Most likely Tigervision did this because TI would not license out its GROM chips to many 3rd party developers. The GROM chip allowed for greater amounts of memory to be put onto a single cartridge, and without the chip you were limited to 8K of ROM. Therefore, in order to fit Espial onto a cartridge Tigervision had it plug into the expansion port, which allowed for more memory than standard cartridges. It also made it more difficult to copy the cartridge.
There is a small red start button on the side of the cartridge casing, which can be used to start or restart the game. Interestingly, the Espial manual tells the player to push the red button on the cartridge in order to start the game instead of going through the cartridge selection screen. This leads one to believe that the start button was a way around TI's Version 2.2 consoles which blocked 3rd party cartridges from appearing on the selection screen. By using a button to start (and also reset) the game it completely bypassed any GROM check that the system might have had.
This game is a port of the 1983 Orca arcade game Espial.