These are Metal Gear's PSP entries, the games that kept the stealth series alive on handhelds in the 2000s. Metal Gear Acid (2004) was the odd one out, a turn-based card game that reimagined sneaking as strategy. Portable Ops (2006) brought back the real-time, action-based stealth and, importantly, the canonical storyline. Peace Walker (2010) went furthest, a near-mainline entry with base-building, co-op missions and a major chapter in Big Boss's story.
For a portable spin-off line, these punched well above their weight, with Peace Walker in particular treated as essential to the series' canon rather than a side dish. A games-only branch, and proof the handheld entries were taken seriously.
The The Portable Entries franchise spans 3 games in the CrossBinge catalog.
Part of Metal Gear.