A robot-themed versus-fighter-shooter game. During the fights, the player controls a robot (called a gotcha-borg) looking into the screen, and runs/jumps around on a field, shooting and battling down other robots, trying to win (similar to games like Virtual-On).
The game's theme is plastic robot toys (the Gotcha Borgs); as that's what the player controls in the fights. It's is heavy in the collectible aspect, as the player has access to several different borgs, and can unlock more as the game proceeds. The game also features a 4-player versus mode, where four players can fight each other, individually or in teams.
The game received mediocre reviews from critics, as well as a lack of advertising, though it remains a cult classic with numerous high fan reviews. Capcom reported 25,000 sold units in 2004. Due to the cult status and generally low amount of copies around, a used copy in premium condition could in Japan fetch prices in the $200 range (source: user's own experience), but was re-released in 2007, selling another 5,000 copies and lowering the second hand prices.
The game was also put in a third release in 2012, on Capcom's own online shop, eCapcom.
Sales details source: Wikipedia, "Gotcha Force", and "ガチャフォース", available under the CC-BY-SA License.