You want to create a language-rich environment in your class. For this, you should:

To create a language-rich environment in a classroom, the target language must be integrated naturally, meaningfully, and continuously into the students' daily surroundings and activities. A language-rich environment is one where students are constantly exposed to the language in various forms and have ample opportunities to interact with it.

Let us analyze the given options to understand why this approach is the most effective:
1. Seeing, noticing, and using the language: When language is displayed around the classroom (such as through charts, labels, word walls, and print-rich displays), learners constantly "see" and "notice" it. Furthermore, when they are given hands-on opportunities to "use" the language through discussions, collaborative tasks, and self-expression, they internalize it naturally. This immersive, active engagement is the foundation of a language-rich classroom.
2. Establishing a language lab: While a language lab can be a helpful resource, it is often a structured, separate facility rather than an everyday, integrated environment within the main classroom where daily interaction happens.
3. Motivating parents to buy games: Shifting the responsibility to parents to buy games does not guarantee a rich linguistic environment within the classroom where the actual instructional learning and peer communication take place.
4. Encouraging the use of "only English": Forcing learners to use only the target language can create performance anxiety and restrict communication, rather than fostering a supportive and natural space for language acquisition.

Therefore, the most comprehensive and learner-centered strategy to foster a language-rich environment is to provide opportunities where the language is seen, noticed, and actively used by the learners in their daily classroom life.